A168086 Numbers k such that d(k) is not an isolated number.

1, 4, 9, 16, 24, 25, 30, 36, 40, 42, 48, 49, 54, 56, 64, 66, 70, 78, 80, 81, 88, 100, 102, 104, 105, 110, 112, 114, 120, 121, 128, 130, 135, 136, 138, 144, 152, 154, 162, 165, 168, 169, 170, 174, 176, 182, 184, 186, 189, 190, 192, 195, 196, 208, 210, 216, 222

Offset

1,2

Comments

A000005 = A167759 U A168086. Where 0,1,3,5,7,8,9,10,11,13,14,15,16,17,19,20,21,22,.. are nonisolated numbers A167707. The nonisolated numbers of divisors of n. The positions of isolated numbers in A000005.

Links

Table of n, a(n) for n=1..57.

Formula

A000005(a(n)) = nonisolated number.

Example

A000005(a(1)=1)=1, A000005(a(2)=4)=3, A000005(a(3)=9)=3.

Crossrefs

Cf. A000005, A167759, A167707.

Sequence in context: A009850 A009853 A008030 * A176238 A139588 A320894

Adjacent sequences: A168083 A168084 A168085 * A168087 A168088 A168089

Keyword

nonn

Author

Juri-Stepan Gerasimov, Nov 18 2009

Extensions

Corrected (132, 140, 148 removed, 152 inserted etc.) by R. J. Mathar, Jun 04 2010

Status

approved