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
Keywords
Links
- Andrew Howroyd, Table of n, a(n) for n = 1..200
Programs
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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
Formula
Inverse Moebius transform of A326888.