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A347611 a(n) is the n-th n-factorial number: a(n) = n!_n. 2
1, 1, 3, 52, 8925, 22661496, 1131162092095, 1375009641495014400, 48378633136349277767794425, 57001313848230245122464621625840000, 2552524038347870310755413660544832496799359491, 4859161865915056755501262525796512204608930674134393036800 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..36

Index entries for sequences related to factorial numbers

FORMULA

a(n) = Product_{j=1..n} (n^j-1)/(n-1) for n > 1, a(0) = a(1) = 1.

a(n) = A069777(n,n).

MAPLE

b:= proc(n, k) option remember; `if`(n<2, 1,

      b(n-1, k)*(k^n-1)/(k-1))

    end:

a:= n-> b(n$2):

seq(a(n), n=0..12);

MATHEMATICA

Array[QFactorial[#, #] &, 12, 0] (* Michael De Vlieger, Sep 09 2021 *)

PROG

(PARI) a(n) = if (n<=1, 1, prod(k=1, n, (n^k-1)/(n-1))); \\ Michel Marcus, Sep 09 2021

(Python)

from math import prod

def a(n):

    return 1 if n <= 1 else prod((n**k - 1)//(n - 1) for k in range(1, n+1))

print([a(n) for n in range(12)]) # Michael S. Branicky, Sep 09 2021

CROSSREFS

Main diagonal of A069777.

Sequence in context: A263530 A136723 A202649 * A302932 A143387 A228452

Adjacent sequences:  A347608 A347609 A347610 * A347612 A347613 A347614

KEYWORD

nonn

AUTHOR

Alois P. Heinz, Sep 08 2021

STATUS

approved

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Last modified May 29 04:32 EDT 2022. Contains 354122 sequences. (Running on oeis4.)