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A277407 a(n) = A277406(n)/(n+1). 3
1, 1, 3, 19, 220, 4196, 120876, 4915212, 268194816, 18903020544, 1671209210880, 181064295924480, 23589442167333120, 3638090042721918720, 655483159341216541440, 136420837710333144595200, 32478481518550347674419200, 8770206330674425311097651200, 2666047809138871800854163456000, 906320525390421790143785781657600, 342508343836409428996994343026688000 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

A277406(n) equals the sum of all permutations of compositions of functions (1 + k*x) for k=1..n, evaluated at x=1.

LINKS

Table of n, a(n) for n=0..20.

FORMULA

a(n) = 1/(n+1) * Sum_{k=0..n} k!*(n-k)! * Sum_{i=0..n-k+1} (-1)^(n-i+1) * Stirling2(i,n-k+1) * Stirling1(n+1,i)).

PROG

(PARI) {a(n) = 1/(n+1) * sum(k=0, n, k!*(n-k)! * sum(i=0, n-k+1, (-1)^(n-i+1) * stirling(i, n-k+1, 2) * stirling(n+1, i, 1)))}

for(n=0, 20, print1(a(n), ", "))

CROSSREFS

Cf. A277405, A277406.

Sequence in context: A001833 A001035 A267634 * A271587 A217906 A166380

Adjacent sequences:  A277404 A277405 A277406 * A277408 A277409 A277410

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Oct 16 2016

STATUS

approved

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Last modified February 23 00:03 EST 2018. Contains 299472 sequences. (Running on oeis4.)