1887900

Appears in sequences

• a(n) = 2*(n+1)*binomial(n+2,4).at n=27A027777
• a(n) = (n+1)*(n+2)^3*(n+3)*(2n+3)*(2n+5)/360.at n=13A107970
• a(n) = (18*n)!*(4*n)!/((12*n)!*(9*n)!*n!).at n=2A295443
• Numbers k such that sigma(k + sigma(k)) = sigma(k) + sigma(sigma(k)), where sigma = A000203.at n=9A376831