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 A112850 #18 Sep 08 2022 08:45:23
%S A112850 2,32,132,576,2540,11112,48076,205952,875196,3695160,15519548,
%T A112850 64899792,270415652,1123264856,4653525660,19234572544,79342611548,
%U A112850 326704870872,1343120024476,5513861152880,22606830726564,92580354403768,378737813469692,1547884976788896,6320530321887700,25787763713301512
%N A112850 Number of graph endomorphisms of undirected cycles of even length: |End(C_2n)|.
%D A112850 M. A. Michels, About The Structure of Graph Endomorphisms, Diploma thesis, University of Oldenburg, Germany, 2005
%H A112850 Vincenzo Librandi, <a href="/A112850/b112850.txt">Table of n, a(n) for n = 1..1000</a>
%H A112850 M. A. Michels and U. Knauer, <a href="http://dx.doi.org/10.1016/j.disc.2008.11.022">The congruence classes of paths and cycles</a>, Discrete Math., 309 (2009), 5352-5359. [_N. J. A. Sloane_, Sep 15 2009]
%F A112850 |End(C_2n)| = 2n*(2 + binomial(2n-1, n-1) + binomial(2n-1, n)) for n > 1.
%t A112850 Join[{2}, Table[2 n (2 + Binomial[2 n - 1, n - 1] + Binomial[2 n - 1, n]), {n, 2, 25}]] (* _Vincenzo Librandi_, Nov 21 2018 *)
%o A112850 (Magma) [2] cat [2*n*(2 + Binomial(2*n-1, n-1) + Binomial(2*n-1, n)): n in [2..30]]; // _Vincenzo Librandi_, Nov 21 2018
%Y A112850 Cf. A112849.
%K A112850 easy,nonn
%O A112850 1,1
%A A112850 Martin Alexander Michels (martinmichels(AT)t-online.de), Sep 24 2005
%E A112850 Corrected first term from 4 to 2 and added "n > 1" in the formula, which is not correct when n=1. - James D. Mitchell (jdm3(AT)st-and.ac.uk), Sep 21 2010