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A350135 Number of endofunctions on [2n] whose smallest connected component has size n. 2
1, 1, 27, 2890, 705740, 310181886, 215071984512, 216357598418676, 298018065222408960, 538758820820128412790, 1237604585414359892787200, 3521561770316172974098259916, 12159265179096745219044911480832, 50086112147669900240287215353718700, 242646275221231775443338250567758643200 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,3
COMMENTS
a(0) = 1 by convention.
Number of endofunctions on [2n] with two connected components of size n.
LINKS
FORMULA
a(n) = A347999(2n,n).
a(n) = A001865(n)^2 * A088218(n) for n >= 1.
EXAMPLE
a(1) = 1: 12.
MAPLE
a:= n-> `if`(n=0, 1, add(n^(n-j)*(n-1)!/(n-j)!, j=1..n)^2*binomial(2*n, n)/2):
seq(a(n), n=0..14);
CROSSREFS
Sequence in context: A048567 A227492 A027363 * A085529 A132659 A104131
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Dec 15 2021
STATUS
approved

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Last modified June 19 00:22 EDT 2024. Contains 373492 sequences. (Running on oeis4.)