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 A267844 #50 Sep 08 2022 08:46:15
%S A267844 3,7,44,375,3724,40572,470448,5705271,71571500,921922716,12130541488,
%T A267844 162422308412,2206718599344,30354522550000,422005129502400,
%U A267844 5921371233163575,83761043464536300,1193351781764231100,17110404580326750000,246734315435589111900
%N A267844 a(n) = Catalan(n)^2*(4n + 3).
%C A267844 Numerator of the modified (4n+3) Wallis-Lambert-series-1 with denominator A013709 convergent to 1. Proof: Both the Wallis-Lambert-series-1=4/Pi-1 and the elliptic Euler-series=1-2/Pi are absolutely convergent series. Thus any linear combination of the terms of these series will be also absolutely convergent to the value of the linear combination of these series - in this case to 1. Q.E.D.
%H A267844 Ralf Steiner, <a href="https://www.researchgate.net/publication/293173020_Notiz_zur_modifizierten_Wallis-Lambert-Reihe">Notiz zur modifizierten Wallis-Lambert-Reihe</a> (in German).
%F A267844 a(n) = Catalan(n)^2*(4n + 3).
%t A267844 Table[CatalanNumber[n]^2 (4 n + 3), {n, 0, 19}] (* _Michael De Vlieger_, Jan 24 2016 *)
%o A267844 (Magma) [Catalan(n)^2*(4*n+3):n in [0..20]]; // _Vincenzo Librandi_, Jan 25 2016
%Y A267844 Cf. A000108, A013709 (denominator).
%K A267844 nonn,frac
%O A267844 0,1
%A A267844 _Ralf Steiner_, Jan 21 2016