258521

Properties

Appears in sequences

• Number of arrays of -4..4 integers x(1..n) with every x(i) in a subsequence of length 1 or 2 with sum zero.at n=9A193644
• a(1) = 2; thereafter, a(n) is the smallest prime not yet used which is compatible with the condition that a(n) is a non-quadratic residue modulo a(k) for the next n indices k = n + 1, n + 2, ..., 2n.at n=31A249797
• Prime numbersat n=22719