172480

Appears in sequences

• Triangular matrix, read by rows, equal to [2*I - A008459]^(-1), i.e., the matrix inverse of the difference of twice the identity matrix and the triangular matrix of squared binomial coefficients.at n=41A102220
• Numbers k not divisible by 6 such that sigma(k) > 3*k.at n=13A126104
• a(n) = Sum_{d|n} A007955(d) * A007955(n/d), where A007955(m) = product of divisors of m.at n=43A174936
• Molecular topological indices of the complete bipartite graphs K_{n,n}.at n=27A192418
• a(n) is the number of non-equivalent permutations of {1,2,...,2n-1} such that no subset of consecutive terms from the permutation sums to 0 modulo 2n, where two permutations are equivalent if one can be obtained from the other by multiplying every entry with an integer relatively prime to 2n and/or reversing the permutation.at n=7A364237