A119723 Numerator of Sum[ (-1)^(k-1) * 1/(Prime[k]-1)^2, {k,1,n}].

1, 3, 13, 113, 2861, 709, 45601, 408809, 49595489, 2426258561, 485934733, 485460413, 2429223061, 2427480661, 1284905668069, 217047437215261, 182605590283392901, 36508279615059377, 36518889897389297

Offset: 1

Author

Alexander Adamchuk, Jun 13 2006

Keywords

• frac
• nonn

Links

• Eric Weisstein's World of Mathematics, Prime Sums.

Crossrefs

Cf. A119686, A006093, A000040, A086242.

Programs

Mathematica

Numerator[Table[Sum[(-1)^(i-1)*1/(Prime[i]-1)^2, {i, 1, n}], {n, 1, 30}]]

Formula

a(n) = numerator[ Sum[ (-1)^(k-1) * 1/(Prime[k]-1)^2, {k,1,n}]].