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 A350135 #17 Dec 20 2021 07:34:30 %S A350135 1,1,27,2890,705740,310181886,215071984512,216357598418676, %T A350135 298018065222408960,538758820820128412790,1237604585414359892787200, %U A350135 3521561770316172974098259916,12159265179096745219044911480832,50086112147669900240287215353718700,242646275221231775443338250567758643200 %N A350135 Number of endofunctions on [2n] whose smallest connected component has size n. %C A350135 a(0) = 1 by convention. %C A350135 Number of endofunctions on [2n] with two connected components of size n. %H A350135 Alois P. Heinz, <a href="/A350135/b350135.txt">Table of n, a(n) for n = 0..193</a> %F A350135 a(n) = A347999(2n,n). %F A350135 a(n) = A001865(n)^2 * A088218(n) for n >= 1. %e A350135 a(1) = 1: 12. %p A350135 a:= n-> `if`(n=0, 1, add(n^(n-j)*(n-1)!/(n-j)!, j=1..n)^2*binomial(2*n, n)/2): %p A350135 seq(a(n), n=0..14); %Y A350135 Cf. A001865, A065456, A088218, A347999. %K A350135 nonn %O A350135 0,3 %A A350135 _Alois P. Heinz_, Dec 15 2021