48954659

Appears in sequences

• a(n) = (2*n^2)^(-1)*Sum_{d|n} (-1)^(n+d)*moebius(n/d)*binomial(2*d,d).at n=18A131868
• Babbage quotients b_p = (binomial(2p-1, p-1) - 1)/p^2 with p = prime(n).at n=6A263882