A378431 Number of cyclic edge cuts in the n-barbell graph.
1, 727, 580369, 943372583, 4393791394153, 73031427044945215, 4761040298703872985897, 1242974526675429334954640663, 1300665117895338817158343055376913, 5449895182361696580039591706226169477735, 91388720915969010273161845143264574586208701497
Offset: 3
Keywords
Links
- Andrew Howroyd, Table of n, a(n) for n = 3..50
- Eric Weisstein's World of Mathematics, Barbell Graph.
- Eric Weisstein's World of Mathematics, Cyclic Edge Cut.
Programs
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PARI
scs(p,q=p) = {serconvol(serlaplace(p),serlaplace(q))} seq(n)={my(g=sum(k=0,n,2^binomial(k,2)*x^k/k!, O(x*x^n)), t=sum(k=1,n,k^(k-2)*x^k/k!, O(x*x^n))); Vec( 4*scs(exp(t), g - (1+log(g)-t)*exp(t)) + 2*scs(g-exp(t)) - scs(intformal(exp(t)*deriv(log(g)-t))) )} \\ Andrew Howroyd, May 27 2025
Formula
Extensions
a(6) onwards from Andrew Howroyd, May 27 2025