167820

Appears in sequences

• Numbers k such that sigma(k^2+1) is a perfect square.at n=25A067465
• Solution of the complementary equation a(n) = a(n-1) + a(n-2) + b(n+1), where a(0) = 1, a(1) = 2, b(0) = 3, b(1) = 4, b(2) = 5, b(3) = 6, and (a(n)) and (b(n)) are increasing complementary sequences.at n=21A296843