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 A098483 #14 Jan 30 2020 21:29:15
%S A098483 1,1,1,1,5,13,25,41,85,205,473,985,2021,4365,9785,21673,46965,101581,
%T A098483 222745,492665,1087237,2388749,5251065,11587529,25633045,56697933,
%U A098483 125345113,277283353,614212133,1361824525,3020426681,6700678377
%N A098483 Expansion of 1/sqrt((1-x)^2-8x^4).
%C A098483 1/sqrt((1-x)^2-4rx^4) expands to sum{k=0..floor(n/2), binomial(n-2k,k)binomial(n-3k,k)r^k}
%H A098483 Vincenzo Librandi, <a href="/A098483/b098483.txt">Table of n, a(n) for n = 0..200</a>
%F A098483 a(n)=sum{k=0..floor(n/2), binomial(n-2k, k)binomial(n-3k, k)2^k}.
%F A098483 D-finite with recurrence: n*a(n) = (2*n-1)*a(n-1) - (n-1)*a(n-2) + 8*(n-2)*a(n-4). - _Vaclav Kotesovec_, Jun 23 2014
%F A098483 a(n) ~ (1+sqrt(1+8*sqrt(2)))^n / (sqrt(33+10*sqrt(2)-sqrt(265+596*sqrt(2))) * sqrt(Pi*n) * 2^(n-3/2)). - _Vaclav Kotesovec_, Jun 23 2014
%t A098483 CoefficientList[Series[1/Sqrt[(1-x)^2-8*x^4], {x, 0, 20}], x] (* _Vaclav Kotesovec_, Jun 23 2014 *)
%o A098483 (PARI) a(n) = sum(k=0, n\2, binomial(n-2*k, k)*binomial(n-3*k, k)*2^k) \\ _Michel Marcus_, Jul 24 2013
%Y A098483 Cf. A098480, A098482, A098484.
%K A098483 easy,nonn
%O A098483 0,5
%A A098483 _Paul Barry_, Sep 10 2004