0,1

a(n) = Determinant( A+A^2+ A^3+ A^4+ A^5+... A^n)

where A is the submatrix A(1..5,1..5)= of the matrix with factorial determinant

A= [[1,1,1,1,1,1,...],[1,2,1,2,1,2,...],[1,2,3,1,2,3,...],[1,2,3,4,1,2,...],

[1,2,3,4,5,1,...],[1,2,3,4,5,6,...],...] note: Determinant A(1..n,1..n)= (n-1)!

G. Balzarotti and P. P. Lava, "Le sequenze di numeri interi", 2008, ed. Hoepli.

a(1)=Determinant(A)=4!=24

seq(Determinant(sum(A^i, i=1..n)), n=1..30);

A111490, A158040, A158041

Sequence in context: A163576 A145408 A088616 this_sequence A147860 A159409 A065142

Adjacent sequences: A158039 A158040 A158041 this_sequence A158043 A158044 A158045

nonn

Giorgio Balzarotti & Paolo P. Lava (greenblue(AT)tiscali.it), Mar 11 2009