OFFSET
1,2
COMMENTS
Prime p divides a((p-1)/2) for p>3. p^2 divides a(p-1) for prime p>3.
FORMULA
MATHEMATICA
Numerator[Table[Sum[Sum[(-1)^(i+1)*1/(i*j)^2, {i, 1, n}], {j, 1, n}], {n, 1, 20}]]
CROSSREFS
KEYWORD
frac,nonn
AUTHOR
Alexander Adamchuk, Jun 25 2006
STATUS
approved