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 A361835 #14 Apr 10 2023 12:50:35
%S A361835 1,2,2,-10,-10,242,-678,-7054,88342,-207646,-6015904,88310862,
%T A361835 -312514816,-8847633338,184252541514,-1269592841970,-17662739133178,
%U A361835 634109114537218,-7914500471718552,-18165019012117450,2936604063787679650,-62899139815867627378
%N A361835 a(n) = Sum_{k=0..n} (-1)^(n-k) * binomial(2*k,k) * binomial(n*k,n-k).
%H A361835 Winston de Greef, <a href="/A361835/b361835.txt">Table of n, a(n) for n = 0..481</a>
%F A361835 a(n) = [x^n] 1/sqrt(1 - 4*x*(1-x)^n).
%o A361835 (PARI) a(n) = sum(k=0, n, (-1)^(n-k)*binomial(2*k, k)*binomial(n*k, n-k));
%Y A361835 Main diagonal of A361834.
%Y A361835 Cf. A361829, A361836.
%K A361835 sign
%O A361835 0,2
%A A361835 _Seiichi Manyama_, Mar 26 2023