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 A227469 #9 Nov 27 2024 17:55:39
%S A227469 1,3,20,245,4554,115192,3709992,145597545,6750522350,361424043596,
%T A227469 21958844607336,1493260499980119,112400273159533800,
%U A227469 9279595605913516080,833858283261973732944,81027308003810095983825,8466793463341565312119830,946776552967215128481968260,112816032067073649248569919400
%N A227469 a(n) = binomial((n+1)^2, n) * (2*n+1) / (n+1)^2 for n>=0.
%F A227469 a(n) = (2*n+1)*A143669(n).
%e A227469 G.f.: A(x) = 1 + 3*x + 20*x^2 + 245*x^3 + 4554*x^4 + 115192*x^5 +...
%o A227469 (PARI) {a(n)=binomial((n+1)^2,n)*(2*n+1)/(n+1)^2}
%o A227469 for(n=0,20,print1(a(n),", "))
%Y A227469 Cf. A143669.
%K A227469 nonn
%O A227469 0,2
%A A227469 _Paul D. Hanna_, Aug 23 2013