A091014 Smallest number having exactly n divisors d such that for some x also d-x and d+x are divisors.

1, 6, 18, 12, 30, 24, 36, 48, 132, 84, 72, 60, 312, 264, 816, 144, 270, 168, 252, 300, 288, 120, 810, 432, 1224, 180, 1188, 1140, 792, 630, 1152, 240, 2112, 672, 4104, 504, 420, 600, 3672, 540, 1872, 480, 2592, 1584, 900, 5100, 360, 2760, 2040, 1890

Offset: 0

Author

Reinhard Zumkeller, Dec 13 2003

Keywords

• nonn

Comments

A091009(a(n))=n and A091009(m)<>n for m<=a(n).

Examples

			a(9)=84: the exactly 9 triples of divisors of 84 with the defining property: (1,2,3), (2,3,4), (2,4,6), (1,4,7), (2,7,12), (3,12,21), (7,14,21), (14,21,28) and (14,28,42).