A081062 Neither 3-smooth numbers nor prime powers.

10, 14, 15, 20, 21, 22, 26, 28, 30, 33, 34, 35, 38, 39, 40, 42, 44, 45, 46, 50, 51, 52, 55, 56, 57, 58, 60, 62, 63, 65, 66, 68, 69, 70, 74, 75, 76, 77, 78, 80, 82, 84, 85, 86, 87, 88, 90, 91, 92, 93, 94, 95, 98, 99, 100, 102, 104, 105, 106, 110, 111, 112, 114, 115, 116

Offset

1,1

Comments

A081060(m) > 1 iff m = a(k) for some k. - corrected by Gionata Neri, Jul 30 2016

Complement of A081061.

Composites with smallest prime factor^largest prime factor > largest prime factor^smallest prime factor. - Juri-Stepan Gerasimov, Jan 04 2009

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Example

12 = 2^2*3 is not in the sequence because it is 3-smooth (all prime factors are 3 or less). 17 = 17^1 and 49 = 7^2 are not in the sequence because they are prime powers. - Michael B. Porter, Jul 31 2016

Maple

filter:= proc(n) local f; f:= numtheory:-factorset(n); nops(f) > 1 and max(f) > 3 end proc:
select(filter, [$1..1000]); # Robert Israel, Jul 31 2016

Mathematica

Select[Range@ 120, Nor[PrimePowerQ@ #, 3 EulerPhi[6 #] == 6 #] &] (* Michael De Vlieger, Aug 02 2016, after Robert G. Wilson v at A003586 *)

Crossrefs

Cf. A003586, A000961.

Sequence in context: A246449 A121836 A317590 * A330136 A307589 A209800

Adjacent sequences: A081059 A081060 A081061 * A081063 A081064 A081065

Keyword

nonn,easy

Author

Reinhard Zumkeller, Mar 04 2003

Status

approved