A069740 Let M_n be the n X n matrix M_(i,j)=1/(i+j+ij); a(n) is the numerator of det(M_n).

1, 1, 1, 1, 4, 1, 64, 4, 65536, 512, 33554432, 65536, 68719476736, 6442450944, 9007199254740992, 281474976710656, 220326730624766167090200576, 340010386766614455386112, 486777830487640090174734030864384

Offset

1,5

Comments

Is a(n) always of the form 2^u*3^v?

Links

Table of n, a(n) for n=1..19.

Prog

(PARI) for(n=1, 70, print1(numerator(matdet(matrix(n, n, i, j, 1/(i*j+i+j)))), ", "))

Crossrefs

Sequence in context: A278578 A368266 A338681 * A173008 A298828 A114917

Adjacent sequences: A069737 A069738 A069739 * A069741 A069742 A069743

Keyword

easy,nonn

Author

Benoit Cloitre, Apr 21 2002

Status

approved