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 A034270 #21 Oct 19 2023 19:44:01
%S A034270 0,1,13,99,605,3289,16653,80444,375972,1715130,7681586,33913385,
%T A034270 148018455,640049865,2746422525,11708971560,49647131160,209523969630,
%U A034270 880668859590,3688555690950,15401089588794,64128925255626,266376231244178,1104047701891624,4566956385797400
%N A034270 f(n,n+3) where f is given in A034261.
%H A034270 Vincenzo Librandi, <a href="/A034270/b034270.txt">Table of n, a(n) for n = 0..1000</a>
%F A034270 a(n) ~ c*sqrt(n)*4^n, with c = 8/sqrt(Pi) = 2*A249521. - _Stefano Spezia_, Oct 19 2023
%t A034270 Table[n*(n^2+4*n+1)*Binomial[2*n+3,n]/((n+4)*(n+5)),{n,0,20}] (* _Vaclav Kotesovec_, Oct 27 2012 *)
%o A034270 (Magma) [n*(n^2+4*n+1)*Binomial(2*n+3, n)/((n+4)*(n+5)): n in [0..25]]; // _Vincenzo Librandi_, May 04 2013
%o A034270 (PARI) a(n)=n*(n^2+4*n+1)*binomial(2*n+3,n)/((n+4)*(n+5)); \\ _Joerg Arndt_, May 04 2013
%Y A034270 Cf. A000302, A034261, A249521.
%K A034270 nonn,easy
%O A034270 0,3
%A A034270 _Clark Kimberling_
%E A034270 Corrected and extended by _N. J. A. Sloane_, Apr 21 2000