A326895 Number of chiral pairs of color loops of length n with integer entries that cover an initial interval of positive integers.

0, 0, 1, 6, 48, 370, 3341, 33966, 393468, 5111100, 73753685, 1170469192, 20263758984, 380047816638, 7676106093049, 166114206920706, 3834434320842720, 94042629507775794, 2442147034668044933, 66942194905680941268, 1931543452344523778392, 58519191359156026158522

Offset

1,4

Links

Andrew Howroyd, Table of n, a(n) for n = 1..200

Formula

Inverse Moebius transform of A326888.

Prog

(PARI) a(n)={sum(k=1, n, -k!*(stirling((n+1)\2, k, 2) + stirling(n\2+1, k, 2))/4 + k!*sumdiv(n, d, eulerphi(d)*stirling(n/d, k, 2))/(2*n))} \\ Andrew Howroyd, Sep 13 2019

Crossrefs

Row sums of A305541.

Cf. A326888.

Sequence in context: A324074 A052625 A326888 * A291033 A155130 A250164

Adjacent sequences: A326892 A326893 A326894 * A326896 A326897 A326898

Keyword

nonn

Author

Andrew Howroyd, Sep 13 2019

Status

approved