2126953

Appears in sequences

• Triangular array: T(n,k) = T(n,n) = 1, T(n,k) = 5*T(n-1, k-1) + 2*T(n-1, k), read by rows.at n=51A119727
• Triangular numbers that are the product of two distinct prime numbers of the form 4*k + 3.at n=20A365849