A127234 a(n) = n! (sum(1..n-1))!.

1, 2, 36, 17280, 435456000, 941525544960000, 257498348545415577600000, 12293098054744302855420641280000000, 134988938425519353794787639744975077376000000000, 434085115076654530026451920435442716425635693068288000000000000

Offset

1,2

Comments

Number of distinct n x n symmetrical matrices containing A000217(n+1) different elements which have that same trace.

Links

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

Mathematica

Table[n! (Sum[x, {x, 1, n-1}])!, {n, 1, 10}]
Table[n!((n(n-1))/2)!, {n, 10}] (* Harvey P. Dale, May 08 2013 *)

Crossrefs

Cf. A127233, A127235.

Sequence in context: A308942 A134366 A265944 * A326961 A181555 A306644

Adjacent sequences: A127231 A127232 A127233 * A127235 A127236 A127237

Keyword

nonn

Author

Artur Jasinski, Jan 09 2007, Jan 11 2007

Extensions

Edited by Jason G. Wurtzel, Oct 08 2010

Corrected and extended by Harvey P. Dale, May 08 2013

Status

approved