A112769 Numbers with more than one prime factor and, in the ordered factorization, at least one exponent is less than the previous exponent when read from left to right.

12, 20, 24, 28, 40, 44, 45, 48, 52, 56, 60, 63, 68, 72, 76, 80, 84, 88, 90, 92, 96, 99, 104, 112, 116, 117, 120, 124, 126, 132, 135, 136, 140, 144, 148, 152, 153, 156, 160, 164, 168, 171, 172, 175, 176, 180, 184, 188, 189, 192, 198, 200, 204, 207, 208, 212, 220

Offset

1,1

Comments

It appears that this sequence lists the integers x such that A085079(n) > n. - Michel Marcus, Jul 30 2015

Links

Seiichi Manyama, Table of n, a(n) for n = 1..10000

Example

90 = 2^1 * 3^2 * 5^1 and 2 > 1, so 90 is in sequence.

Mathematica

mopfQ[n_]:=Module[{e=FactorInteger[n][[All, 2]]}, Length[e]>1&&Min[ Differences[ e]]<0]; Select[Range[300], mopfQ] (* Harvey P. Dale, May 30 2018 *)

Prog

(PARI) isok(n) = {f = factor(n)[, 2]; if (#f > 1, for (k=2, #f, if (f[k] < f[k-1], return (1)); ); ); return (0); } \\ Michel Marcus, Jul 30 2015

Crossrefs

Cf. A097318, A097319, A097320, A304678.

Sequence in context: A316597 A329142 A362620 * A360253 A097320 A332956

Adjacent sequences: A112766 A112767 A112768 * A112770 A112771 A112772

Keyword

nonn

Author

Ray Chandler, Sep 23 2005, based on a suggestion from Leroy Quet

Status

approved