A118232 Column 1 of triangle A118231.

1, -2, -2, 4, -2, 2, 4, -6, -4, 6, -4, 4, 14, -14, -8, 8, -16, 18, 8, -12, 6, -6, -6, -10, 28, -6, -10, 4, -2, 4, -8, -2, -18, 48, -20, 0, 54, -70, -18, 32, -76, 86, 62, 14, 14, -110, -40, 124, 62, 94, -24, -224, -66, 224, 134, 62, -72, -286, 14, 8, -14, 474, 10, -458

Offset

1,2

Links

Table of n, a(n) for n=1..64.

Prog

(PARI) {a(n)=(matrix(n, n, r, c, if(r>=c, if(gcd(r-c+1, c)==1, 1, 0)))^-2)[n, 1]}

Crossrefs

Cf. A118231.

Sequence in context: A072301 A127171 A215655 * A115070 A064145 A213431

Adjacent sequences: A118229 A118230 A118231 * A118233 A118234 A118235

Keyword

sign

Author

Leroy Quet, Paul D. Hanna, Apr 16 2006

Status

approved