69378

Appears in sequences

• Numbers of the form prime(n) + prime(n+1) - 2 that are also triangular numbers, T(k) = k(k+1)/2.at n=28A110891
• Sum of the numbers in row n of the array at A242364.at n=18A243735
• Triangular numbers n with digits d_1, d_2, ..., d_k such that d_1*(d_1+1)/2 + ... + d_k*(d_k+1)/2 is a triangular number.at n=43A254957