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 A375293 #11 Aug 10 2024 11:03:11
%S A375293 1,1,1,1,0,-3,-8,-15,-23,-26,-12,37,144,326,564,753,633,-281,-2699,
%T A375293 -7346,-14333,-21858,-24097,-8635,45094,162928,362513,620686,813906,
%U A375293 633510,-495381,-3408175,-8939865,-17141831,-25663802,-27145201,-6079518,62953931
%N A375293 Expansion of 1/sqrt((1 - x + x^4)^2 + 4*x^5).
%F A375293 n*a(n) = (2*n-1)*a(n-1) - (n-1)*a(n-2) - 2*(n-2)*a(n-4) - (2*n-5)*a(n-5) - (n-4)*a(n-8).
%F A375293 a(n) = Sum_{k=0..floor(n/4)} (-1)^k * binomial(n-3*k,k)^2.
%o A375293 (PARI) my(N=40, x='x+O('x^N)); Vec(1/sqrt((1-x+x^4)^2+4*x^5))
%o A375293 (PARI) a(n) = sum(k=0, n\4, (-1)^k*binomial(n-3*k, k)^2);
%Y A375293 Cf. A375021, A375292.
%Y A375293 Cf. A246883.
%K A375293 sign
%O A375293 0,6
%A A375293 _Seiichi Manyama_, Aug 10 2024