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 A050490 #26 Jul 08 2023 04:03:39
%S A050490 1,12,46,170,630,2352,8844,33462,127270,486200,1864356,7171892,
%T A050490 27665596,106977600,414538200,1609344270,6258307590,24373220520,
%U A050490 95050101300,371125269900,1450670612820,5676173948640,22230262964520,87137141867100,341824599040860,1341897206800752
%N A050490 a(n) = C(n)*(11n+1) where C(n) = Catalan numbers (A000108).
%D A050490 Albert H. Beiler, Recreations in the Theory of Numbers, Dover, N.Y., 1964, pp. 194-196.
%H A050490 Andrew Howroyd, <a href="/A050490/b050490.txt">Table of n, a(n) for n = 0..200</a>
%F A050490 From _R. J. Mathar_, Feb 13 2015: (Start)
%F A050490 5*(n+1)*a(n) + (-29*n-1)*a(n-1) + 18*(2*n-3)*a(n-2) = 0.
%F A050490 -(n+1)*(11*n-10)*a(n) + 2*(11*n+1)*(2*n-1)*a(n-1) = 0. (End)
%F A050490 G.f.: (5 - 9*x - 5*sqrt(1 - 4*x))/(x*sqrt(1 - 4*x)). - _Amiram Eldar_, Jul 08 2023
%t A050490 Table[CatalanNumber[n](11n+1),{n,0,20}] (* _Harvey P. Dale_, Jul 12 2018 *)
%o A050490 (Magma) [Catalan(n)*(11*n+1):n in [0..25] ]; // _Marius A. Burtea_, Jan 05 2020
%Y A050490 Column k=11 of A330965.
%Y A050490 Cf. A017281, A027810, A000108.
%K A050490 easy,nonn
%O A050490 0,2
%A A050490 _Barry E. Williams_, Dec 27 1999
%E A050490 Terms a(21) and beyond from _Andrew Howroyd_, Jan 05 2020