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

0,2

Comments

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

Links

Table of n, a(n) for n=0..49.

Example

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).

Crossrefs

Sequence in context: A129870 A331056 A274877 * A097370 A252897 A174904

Adjacent sequences: A091011 A091012 A091013 * A091015 A091016 A091017

Keyword

nonn

Author

Reinhard Zumkeller, Dec 13 2003

Status

approved