0,1

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

where A is the submatrix A(1..6,1..6)= 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)=5!=120

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

A111490, A158040, A158041, A158042

Sequence in context: A068296 A123380 A008701 this_sequence A009767 A003789 A046987

Adjacent sequences: A158040 A158041 A158042 this_sequence A158044 A158045 A158046

nonn

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