431056

Appears in sequences

• Triangular numbers n such that sigma(n) is a square number.at n=23A256151
• a(n) is the smallest number of the form 2^k * p * (2^(k+1) * p + 1) where 2 < p < 2^(k+1) is the n-th prime and 2^(k+1) * p + 1 is prime, or -1 if no such number exists.at n=8A370209