40880

Appears in sequences

• Let sigma_m (n) be result of applying sum-of-divisors function m times to n; call n (m,k)-perfect if sigma_m (n) = k*n; sequence gives the (3,k)-perfect numbers.at n=23A019292
• a(n) = T(n,n-3), T given by A026568. Also a(n) = number of integer strings s(0),...,s(n) counted by T, such that s(n)=3.at n=11A026572
• Duplicate of A026572.at n=11A026588
• Theta series of E_8 lattice with respect to midpoint of edge.at n=13A045819
• Number of ternary Lyndon words whose digits sum to 0 mod 3; also number of trace 0 irreducible polynomials over GF(3).at n=12A046209
• Number of ternary Lyndon words whose digits sum to 1 (or 2) mod 3; number of trace 1 (or 2) monic irreducible polynomials over GF(3).at n=12A046211
• Expansion of 1/(1 - 2*x - 2*x^2 - 3*x^3).at n=10A077834
• a(0) = 1, a(n) = 20*sigma[3](n).at n=12A091983
• Fermat quotient of the n-th prime with base 3.at n=3A146211
• G.f.: A(x) = exp( Sum_{n>=1} 2*sigma(n,n-1)*x^n/n ).at n=7A158095
• Carlitz compositions of n into odd parts.at n=34A218694
• G.f.: exp( Sum_{n>=1} x^n/n * Product_{k>=1} 1/(1 - x^(n*k)*(1 + x^n)^k) ).at n=13A219230
• Total number of congruence subgroups of PSL(2,Z) of genus n.at n=15A258691
• Numbers k such that (3^ord(3, k) - 1)/k is prime, where ord(3, k) is the multiplicative order of 3 (mod k).at n=31A297363
• a(n) = 5*(3*n+1)*(9*n+8)/2 (n>=0).at n=24A304508
• Sum of binomial(Y(2,p), 2) over the partitions p of n, where Y(2,p) is the number of part sizes with multiplicity 2 or greater in p.at n=32A304825
• Numbers k such that the sum of the norm of divisors of k in Gaussian integers is divisible by k.at n=34A332736
• Consecutive states of the linear congruential pseudo-random number generator (257*s + 41) mod 2^16 when started at s=1.at n=23A384961