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 A127131 #6 Jan 28 2020 22:29:10
%S A127131 1,1,4,23,175,1650,18451,237703,3457763,55967155,996755108,
%T A127131 19360232181,407152004331,9215091412811,223307281633261,
%U A127131 5768104533416742,158197552561322216,4591028199312877166,140551293414196198297
%N A127131 Self-convolution square-root of column 1 (A127128) of triangle A127126.
%H A127131 G. C. Greubel, <a href="/A127131/b127131.txt">Table of n, a(n) for n = 0..80</a>
%t A127131 T[n_, k_]:= T[n, k]= If[k==n, 1, Coefficient[(1 +x*Sum[x^(r-k-1)*Sum[T[r, c], {c,k+1,r}], {r,k+1,n}] +x^(n+1))^(k+1), x, n-k]]; CoefficientList[Series[ (Sum[T[n, 1]*x^n, {n,0,22}]/x)^(1/2), {x,0,20}], x] (* _G. C. Greubel_, Jan 28 2020 *)
%Y A127131 Cf. A127126, A127127, A127128, A127129, A127130, A127132, A127133, A127134, A127135.
%K A127131 nonn
%O A127131 0,3
%A A127131 _Paul D. Hanna_, Jan 05 2007