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

Author

Juri-Stepan Gerasimov, Nov 18 2009

Keywords

• nonn

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.

Examples

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

Crossrefs

Cf. A000005, A167759, A167707.

Formula

A000005(a(n)) = nonisolated number.

Extensions

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