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A090603 Number of n-element labeled groupoids with a fixed identity. 2
1, 2, 81, 262144, 152587890625, 28430288029929701376, 2651730845859653471779023381601, 178405961588244985132285746181186892047843328, 11790184577738583171520872861412518665678211592275841109096961 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Also labeled partial groupoids with n-1 elements.

LINKS

Table of n, a(n) for n=1..9.

Eric Weisstein's World of Mathematics, Groupoid.

Index entries for sequences related to groupoids

FORMULA

a(n) = n^((n-1)^2). - Alois P. Heinz, Jul 30 2012

MAPLE

seq(mul(mul(k*n/j, j=2..n), k=2..n), n=0..9); # Zerinvary Lajos, Jun 01 2007

a:=n->mul(mul(sum(1, j=0..n), k=1..n), m=1..n): seq(a(n), n=0..7); # Zerinvary Lajos, Dec 31 2008

with(finance):seq(futurevalue(1, n, n^2), n=0..8); # Zerinvary Lajos, Mar 25 2009

MATHEMATICA

Table[n^(n-1)^2, {n, 10}] (* Harvey P. Dale, May 31 2019 *)

CROSSREFS

Sequence in context: A302722 A123177 A209585 * A020955 A230398 A120826

Adjacent sequences:  A090600 A090601 A090602 * A090604 A090605 A090606

KEYWORD

nonn

AUTHOR

Christian G. Bower, Dec 05 2003

STATUS

approved

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Last modified February 24 07:19 EST 2020. Contains 332199 sequences. (Running on oeis4.)