88680

Appears in sequences

• Numbers k such that 3*R_k + 4 is prime, where R_k = 11...1 is the repunit (A002275) of length k.at n=19A099411
• a(n) = Sum_{0<=j<=n, 0<=k<=n} binomial(n,j)^2 * binomial(n,k)^2 * binomial(n+j,n) * binomial(n+k,n) * binomial(j+k,n).at n=3A220119
• a(n) = Sum_{d|n} (-1)^omega(n/d) * phi(rad(n/d)) * p(d), where p = A000041 (partition numbers).at n=44A333697