A105746 a(n) = minimal c>0 such that (n+1)^2+4*n*c = d^2 is a square.

3, 2, 4, 6, 8, 3, 12, 14, 16, 6, 20, 4, 24, 9, 7, 30, 32, 12, 36, 5, 8, 15, 44, 11, 48, 18, 52, 9, 56, 6, 60, 62, 15, 24, 20, 10, 72, 27, 16, 21, 80, 7, 84, 14, 11, 33, 92, 20, 96, 36, 23, 15, 104, 39, 12, 8, 24, 42, 116, 19, 120, 45, 39, 126, 35, 13, 132, 20, 31, 17, 140, 9, 144, 54