49525domain: NAppears in sequencesa(n) = a(n-1) + 3*a(n-2) -2*a(n-3) - 2*a(n-4), where a(0) = 1, a(1) = 3, a(2) = 5, a(3) = 7.at n=21A295717Expansion of exp( Sum_{k>=1} binomial(8*k-1,2*k) * x^k/k ).at n=3A381745a(0) = 1; a(n) = a(n-1) + Sum_{k=0..n-1} (1 + k) * k^4 * binomial(n-1,k) * a(k) * a(n-1-k).at n=4A386507