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)! a(n) is even with respect to signs of power of A.

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*(-1)^(i-1), i=1..n)), n=1..30);

A111490, A158040, A158041, A158042, A158043, A158044, A158045, A158046, A158047

Sequence in context: A105943 A052721 A060490 this_sequence A052722 A139389 A166596

Adjacent sequences: A158045 A158046 A158047 this_sequence A158049 A158050 A158051

sign

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