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 A385203 #9 Jun 21 2025 11:50:32 %S A385203 1,5,0,-125,625,5625,-87500,0,9140625,-60156250,-653125000, %T A385203 11654296875,0,-1470068359375,10353515625000,118916992187500, %U A385203 -2225148925781250,0,302784667968750000,-2199076690673828125,-25952287445068359375,497460246276855468750,0 %N A385203 G.f. A(x) satisfies A(x) = ( 1 + 25*x*A(x)^2 )^(1/5). %F A385203 a(n) = 25^n * binomial(2*n/5+1/5,n)/(2*n+1). %F A385203 G.f. A(x) satisfies A(x) = 1/A(-x/A(x)). %F A385203 G.f.: ( (1/x) * Series_Reversion(x/(1+25*x)^(2/5)) )^(1/2). %F A385203 a(5*n+2) = 0 for n >= 0. %o A385203 (PARI) a(n) = 25^n*binomial(2*n/5+1/5, n)/(2*n+1); %Y A385203 Cf. A078534, A385204, A385205. %K A385203 sign %O A385203 0,2 %A A385203 _Seiichi Manyama_, Jun 21 2025