

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.


3



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
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OFFSET

1,4


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.


LINKS

Table of n, a(n) for n=1..77.


PROG

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


CROSSREFS

Sequence in context: A094266 A286335 A291652 * A261835 A286932 A259475
Adjacent sequences: A071566 A071567 A071568 * A071570 A071571 A071572


KEYWORD

easy,sign


AUTHOR

Benoit Cloitre, May 30 2002


STATUS

approved



