A176238 Natural numbers n such that d(d(n)+1) > 2

4, 9, 16, 24, 25, 30, 36, 40, 42, 49, 54, 56, 64, 66, 70, 78, 81, 88, 100, 102, 104, 105, 110, 114, 121, 128, 130, 135, 136, 138, 144, 152, 154, 165, 169, 170, 174, 182, 184, 186, 189, 190, 192, 195, 196, 222, 225, 230, 231, 232, 238, 240, 246, 248, 250, 255

Offset

1,1

Comments

Complement to A166546.

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Mathematica

Select[Range[300], DivisorSigma[0, DivisorSigma[0, #]+1]>2&] (* Harvey P. Dale, Jul 15 2021 *)

Crossrefs

Cf. A000005, A166546.

Sequence in context: A009853 A008030 A168086 * A139588 A320894 A122986

Adjacent sequences: A176235 A176236 A176237 * A176239 A176240 A176241

Keyword

nonn

Author

Giovanni Teofilatto, Apr 12 2010

Extensions

Extended by Giovanni Teofilatto, Apr 14 2010

Corrected (192 and 240 inserted) by R. J. Mathar, Apr 22 2010

Status

approved