A071569 Det(M_n) where M_n is the n X n matrix m(i,j)=1 if floor(i/j) is even, 0 otherwise.

0, -1, 0, -2, 1, 0, -1, -3, 3, -2, 1, 1, -2, 3, -2, -6, 5, -5, 4, -2, 3, -2, 1, 3, -3, 4, -4, 6, -7, 6, -7, -9, 10, -9, 10, -10, 9, -8, 9, -5, 4, -5, 4, -2, 2, -1, 0, 8, -8, 8, -7, 9, -10, 10, -9, 13, -12, 13, -14, 12, -13, 14, -14, -18, 19, -20, 19, -17, 18, -19, 18, -18, 17, -16, 16, -14, 15

Offset: 1

Author

Benoit Cloitre, May 30 2002

Keywords

• easy
• sign

Comments

Det(Q_n) = 1 if Q_n denotes the n X n matrix defined by: m(i,j)=1 if floor(i/j) is odd, 0 otherwise, since this matrix is triangular with 1's on the main diagonal.

Programs

PARI

for(n=1,70,print1(matdet(matrix(n,n,i,j,if((-1)^(sigma(i+j))+1,1,0))),","))