Run LODA programs in your browser. Examples to try out:

A000010 Euler totient function.
A000120 1’s-counting sequence.
A002994 Initial digit of cubes.
A003188 Decimal equivalent of Gray code for n.
A007318 Pascal’s triangle read by rows.

Advanced examples

A001113 Decimal expansion of e.
A002487 Stern’s diatomic series.
A002708 a(n) = Fibonacci(n) mod n.
A003132 Sum of squares of digits of n.
A003986 Table of x OR y, where (x,y) = (0,0), (0,1), (1,0), (0,2), (1,1), (2,0), …
A003987 Table of n XOR m (or Nim-sum of n and m) read by antidiagonals, i.e., with entries in the order (n,m) = (0,0), (0,1), (1,0), (0,2), (1,1), (2,0), …
A003991 Multiplication table read by antidiagonals: T(i,j) = i*j, i>=1, j>=1.
A004185 Arrange digits of n in increasing order, then (for n>0) omit the zeros.
A004186 Arrange digits of n in decreasing order.
A004198 Table of x AND y, where (x,y) = (0,0),(0,1),(1,0),(0,2),(1,1),(2,0),…
A005590 a(0) = 0, a(1) = 1, a(2n) = a(n), a(2n+1) = a(n+1) - a(n).
A006577 Number of halving and tripling steps to reach 1 in ‘3x+1’ problem, or -1 if 1 is never reached.
A007305 Numerators of Farey (or Stern-Brocot) tree fractions.
A007434 Jordan function J_2(n) (a generalization of phi(n)).
A008330 phi(p-1), as p runs through the primes.
A030101 a(n) is the number produced when n is converted to binary digits, the binary digits are reversed and then converted back into a decimal number.
A030102 Base-3 reversal of n (written in base 10).
A036839 RATS(n): Reverse Add Then Sort the digits.
A037861 (Number of 0’s) - (number of 1’s) in the base-2 representation of n.
A046901 a(n) = a(n-1) - n if a(n-1) > n, else a(n) = a(n-1) + n.
A047679 Denominators in full Stern-Brocot tree.
A050873 Triangular array T read by rows: T(n,k) = gcd(n,k).
A052126 a(1) = 1; for n>1, a(n)=n/(largest prime dividing n).
A053222 First differences of sigma(n).
A056539 Self-inverse permutation: reverse the bits in binary expansion of n and also complement them (0->1, 1->0) if the run count (A005811) is even.
A057889 Bit-reverse of n, including as many leading as trailing zeros.
A059893 Reverse the order of all but the most significant bit in binary expansion of n: if n = 1ab..yz then a(n) =
A063114 n + product of nonzero digits of n.
A064989 Multiplicative with a(2^e) = 1 and a(p^e) = prevprime(p)^e for odd primes.
A065075 Sum of digits of the sum of the preceding numbers.
A065620 a(0)=0; thereafter a(2n) = 2a(n), a(2n+1) = -2a(n) + 1.
A066520 Number of primes of the form 4m+3 <= n minus number of primes of the form 4m+1 <= n.
A073138 Largest number having in its binary representation the same number of 0’s and 1’s as n.
A087909 a(n) = Sum_{d|n} (n/d)^(d-1).
A093873 Numerators in Kepler’s tree of harmonic fractions.
A129594 Involution of nonnegative integers induced by the conjugation of the partition encoded in the run lengths of binary expansion of n.
A151949 a(n) = image of n under the Kaprekar map n -> (n with digits sorted into descending order) - (n with digits sorted into ascending order).
A155043 a(0)=0; for n >= 1, a(n) = 1 + a(n-d(n)), where d(n) is the number of divisors of n (A000005).
A160595 Numerator of resilience R(n) = phi(n)/(n-1), with a(1) = 1 by convention.
A175851 a(n) = 1 for noncomposite n, a(n) = n - previousprime(n) + 1 for composite n.
A186690 Expansion of - (1/8) theta_3’’(0, q) / theta_3(0, q) in powers of q.
A220466 a((2*n-1)*2^p) = 4^p*(n-1) + 2^(p-1)*(1+2^p), p >= 0 and n >= 1.
A227183 a(n) is the sum of parts of the unique unordered partition encoded in the run lengths of the binary expansion of n; row sums of A227739 for n >= 1.
A243499 Product of parts of integer partitions as enumerated in the table A125106.
A276086 Prime product form of primorial base expansion of n: digits in primorial base representation of n become the exponents of successive prime factors whose product a(n) is.
A276150 Sum of digits when n is written in primorial base (A049345); minimal number of primorials (A002110) that add to n.
A289813 A binary encoding of the ones in ternary representation of n.
A289814 A binary encoding of the twos in ternary representation of n.
A306367 a(n) = numerator of (n^2 + 2)/(n + 2).
A318458 a(n) = n AND A001065(n), where AND is bitwise-and (A004198) & A001065 = sum of proper divisors.
A328572 Primorial base expansion of n converted into its prime product form, but with 1 subtracted from all nonzero digits: a(n) = A003557(A276086(n)).
A336466 Fully multiplicative with a(p) = A000265(p-1) for any prime p, where A000265(k) gives the odd part of k.
A340649 a(n) = (n*prime(n+1)) mod prime(n).
A342730 a(n) = floor((frac(e*n) + 1) * prime(n+1)).