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 A377237 #11 May 03 2025 04:58:50
%S A377237 1,2,10,56,326,1936,11644,70672,431942,2654816,16392564,101611536,
%T A377237 631938524,3941350816,24643020344,154415141152,969445760070,
%U A377237 6096812777664,38401653547204,242213348616592,1529642560685684,9671100898555168,61208631472013256,387759384222157152
%N A377237 Expansion of 1/sqrt(1 - 4*x/sqrt(1 - 4*x)).
%F A377237 a(n) = 4^n * Sum_{k=0..n} (-1)^k * binomial(-1/2,k) * binomial(n-k/2-1,n-k).
%F A377237 a(n) ~ 2^(n+1) * (1 + sqrt(5))^(n - 1/2) / (5^(1/4) * sqrt(Pi*n)). - _Vaclav Kotesovec_, May 03 2025
%o A377237 (PARI) a(n) = 4^n*sum(k=0, n, (-1)^k*binomial(-1/2, k)*binomial(n-k/2-1, n-k));
%Y A377237 Cf. A011782, A377238.
%Y A377237 Cf. A377239.
%K A377237 nonn
%O A377237 0,2
%A A377237 _Seiichi Manyama_, Oct 21 2024