A392135 Third column of A391957.

0, 0, 0, 0, 0, 9, 7, 5, 3, 1, 18, 14, 10, 6, 2, 27, 21, 15, 9, 3, 36, 28, 20, 12, 4, 94, 82, 70, 58, 46, 93, 79, 65, 51, 37, 92, 76, 60, 44, 28, 91, 73, 55, 37, 19, 90, 70, 50, 30, 10, 188, 164, 140, 116, 92, 177, 151, 125, 99, 73, 166, 138, 110, 82, 54, 155, 125

Offset

0,6

Comments

Powers of 5 in the factorization of A391956.

The first 82 terms were obtained from a brute force calculation of A391956. From these results a regular pattern is observed to determine more terms.

See also A391957 for a Python program.

Links

A.H.M. Smeets, Table of n, a(n) for n = 0..10000

Formula

a(5^n) = 5*a(5^(n-1)) + 2*5^n - 1, a(1) = 0.

Conjectured: a(j*5^m + 5^(m-1)*k) = a(j*5^m) + k*(a(5^(m-1)) - 2*5^(m-1)*Sum_{i = 1..j} A055457(i)), 0 < k < 5, where a(j*5^m) = j*a(5^(m-1)) for j < 5.

Crossrefs

Cf. A055457, A391956, A391957.

Sequence in context: A109846 A096230 A114433 * A222129 A188141 A244667

Adjacent sequences: A392132 A392133 A392134 * A392136 A392137 A392138

Keyword

nonn

Author

A.H.M. Smeets, Jan 01 2026

Status

approved