127007

Appears in sequences

• Numbers k such that (k+1)*phi(k) is a perfect square.at n=36A069952
• Composite numbers k such that (k+1)*sigma(k) is a perfect square.at n=21A073586
• Triangle T(n,k) = 2*binomial(n,k)^2 - 1, read by rows, 0<=k<=n.at n=60A141597
• a(n) = (n + 1)*(20*n^2 + 19*n + 6)/6.at n=33A220084