71600domain: NAppears in sequencesa(n) = 31250*n - 22150.at n=2A157619Numbers k such that 9*R_(k+2) - 4*10^k is prime, where R_k = 11...1 is the repunit (A002275) of length k.at n=22A257039Expansion of Product_{k>=1} 1/(1 - (4*k-1)*x^(4*k-1)).at n=32A265828Expansion of e.g.f. (Sum_{k>=0} binomial(3*k,k) * x^k)^(1/3).at n=5A386365