This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A290755 #16 May 29 2025 21:54:52
%S A290755 1,0,1,5,49,759,16081,435833,14517441,579937319,27203499361,
%T A290755 1474723875789,91200920752129,6365087902895747,496792437580978449,
%U A290755 43025414912824996889,4106965602739453756801,429531453143336097416367,48964278165034713331278529,6055596695306076807138311717,809134978410285605488807023681
%N A290755 Number of minimal edge covers in the n-crown graph.
%H A290755 Andrew Howroyd, <a href="/A290755/b290755.txt">Table of n, a(n) for n = 0..60</a>
%H A290755 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/CrownGraph.html">Crown Graph</a>.
%H A290755 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/MinimalEdgeCover.html">Minimal Edge Cover</a>.
%o A290755 (PARI) \\ by inclusion-exclusion.
%o A290755 B(n,k)={ my(xe=exp(x+O(x*x^n)), ye=exp(y+O(y*y^n))); n!^2*polcoef(polcoef((xe+ye-1)^k*exp(x*ye + y*xe - (x+y+x*y)),n),n)}
%o A290755 a(n) = {sum(k=0, n, binomial(n,k)*B(n-k,k)*(-1)^k)} \\ _Andrew Howroyd_, May 29 2025
%Y A290755 Cf. A210655.
%K A290755 nonn
%O A290755 0,4
%A A290755 _Eric W. Weisstein_, Aug 09 2017
%E A290755 a(6)-a(8) from _Giovanni Resta_, Aug 10 2017
%E A290755 a(1)-a(2) inserted by _Eric W. Weisstein_, Feb 14 2022
%E A290755 a(0)=1 prepended and a(9) onwards from _Andrew Howroyd_, May 29 2025