a(n) = s(1)*s(2)*...*s(n+1)(1/s(2) - 1/s(3) + ... + c/s(n+1)), where c=(-1)^n+1 and s(k) = 3k-2 for k = 1,2,3,...

A024218

a(n) = s(1)*s(2)*...*s(n+1)(1/s(2) - 1/s(3) + ... + c/s(n+1)), where c=(-1)^n+1 and s(k) = 3k-2 for k = 1,2,3,...