121451

Appears in sequences

• Numbers n of the form p^2-p-1 = A165900(p), for prime p, such that n^2-n-1 = A165900(n) is also prime.at n=15A237527
• a(n) = (p_n + 1)*q_n - 1; where (p_n, q_n) is the n-th twin prime pair.at n=20A328493