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

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

Offset: 1

Author

Artur Jasinski, Jan 09 2007, Jan 11 2007

Keywords

• nonn

Comments

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

Crossrefs

Cf. A127233, A127235.

Programs

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 *)

Extensions

Edited by Jason G. Wurtzel, Oct 08 2010

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