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A023813 a(n) = n^(n*(n+1)/2). 7
1, 8, 729, 1048576, 30517578125, 21936950640377856, 459986536544739960976801, 324518553658426726783156020576256, 8727963568087712425891397479476727340041449, 10000000000000000000000000000000000000000000000000000000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Determinant of n X n matrix M_(i,j) = binomial(n*i,j). - Benoit Cloitre, Sep 13 2003

Number of commutative binary operations on an n-set. Labeled commutative groupoids.

LINKS

Table of n, a(n) for n=1..10.

Eric Postpischil Posting to sci.math newsgroup, May 21 1990

Index entries for sequences related to groupoids

FORMULA

a(n) = Product_{k=1..n} n^k. - José de Jesús Camacho Medina, Jul 12 2016

MAPLE

seq(mul(n^k, k=1..n), n=0..10); # Zerinvary Lajos, Jun 03 2007

MATHEMATICA

Table[n^((n^2 + n)/2), {n, 1, 10}]  (* Geoffrey Critzer, Jan 27 2013 *)

CROSSREFS

a(n) + A079182(n) = A002489(n).

Cf. A001425, A002489, A023814, A023815.

Sequence in context: A017007 A268250 A268106 * A068895 A115590 A134923

Adjacent sequences:  A023810 A023811 A023812 * A023814 A023815 A023816

KEYWORD

easy,nonn

AUTHOR

Lyle Ramshaw (ramshaw(AT)pa.dec.com)

EXTENSIONS

Better description from Amarnath Murthy, Dec 29 2001

STATUS

approved

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Last modified April 26 17:21 EDT 2017. Contains 285449 sequences.