A353209 Number of graph minors in the n-node wheel graph.
1, 3, 7, 18, 46, 122, 326, 863, 2252, 5757, 14430, 35531, 86215, 206613, 490247, 1153733, 2696961, 6268921, 14502345, 33410523, 76691414, 175465674, 400268753, 910604494, 2066396936, 4678171694, 10567687439, 23822090548, 53595047261, 120353301562, 269786130398, 603734094052
Offset: 1
Keywords
Links
- Andrew Howroyd, Table of n, a(n) for n = 1..1000
- Andrew Howroyd, Derivation of formula, Jun 2025.
- Eric Weisstein's World of Mathematics, Graph Minor.
- Eric Weisstein's World of Mathematics, Wheel Graph.
Crossrefs
Cf. A353213.
Programs
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PARI
\\ DIK is unlabeled bracelet transform. EulerT(v)={Vec(exp(x*Ser(dirmul(v,vector(#v,n,1/n))))-1, -#v)} DIK(p, n)={(sum(d=1, n, eulerphi(d)/d*log(subst(1/(1+O(x*x^(n\d))-p), x, x^d))) + ((1+p)^2/(1-subst(p, x, x^2))-1)/2)/2} seq(n)={ my(A=O(x*x^n), gc = x^2*(1 + x + x^2 + 2*x^3 + 2*x^5 - x^7 - x^8 - 2*x^9)/((1 - x)^4*(1 + x)^2*(1 + x^2)*(1 + x + x^2)), gw = x*(DIK(x/(1 - x), n) - x*(1 + x)/(1 - x)), gb = x^2*Ser(EulerT(Vec(x*(1 - x - x^2)/((1 - x)*(1 - 2*x)*(1 - 2*x^2)) + A)))); Vec(((1 + gb - gc)/eta(x + A) + gw - 1)/(1 - x)); } \\ Andrew Howroyd, Jun 18 2025
Extensions
a(12) from Eric W. Weisstein, Mar 15 2023
a(13)-a(18) from Eric W. Weisstein, Oct 11-20 2023
a(1)-a(3) prepended and a(19) onwards from Andrew Howroyd, Jun 18 2025
Comments