75615domain: NAppears in sequencesSum of the prime factors of k equals half the sum of the prime factors of k + 1.at n=24A074213Numbers k such that {k + 2, k + 4} and {k^3 + 2, k^3 + 4} are twin prime pairs.at n=19A284058a(n) = Sum_{k=0..n} binomial(n+k-1,k) * binomial(n+k-1,n-k).at n=7A378565