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A097320
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Numbers with more than one prime factor and, in the ordered factorization, the exponent always decreases when read from left to right.
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3
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12, 20, 24, 28, 40, 44, 45, 48, 52, 56, 63, 68, 72, 76, 80, 88, 92, 96, 99, 104, 112, 116, 117, 124, 135, 136, 144, 148, 152, 153, 160, 164, 171, 172, 175, 176, 184, 188, 189, 192, 200, 207, 208, 212, 224, 232, 236, 244, 248, 261, 268, 272, 275, 279, 284, 288
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| If n = Sum[k=1..m, p(k)^e(k)], then k>1, e(1) > e(2) >...> e(m).
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EXAMPLE
| 80 is 2^4 * 5^1 and 4>1, so 80 is in sequence.
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PROG
| (PARI) for(n=1, 320, F=factor(n):t=0:s=matsize(F)[1]: if(s>1, for(k=1, s-1, if(F[k, 2]<=F[k+1, 2], t=1:break)): if(!t, print1(n", "))))
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CROSSREFS
| Subset of A005117 and A097318 and A112769. Cf. A097319.
Sequence in context: A065201 A136724 A112769 * A204825 A111592 A111947
Adjacent sequences: A097317 A097318 A097319 * A097321 A097322 A097323
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KEYWORD
| nonn
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AUTHOR
| Ralf Stephan, Aug 04 2004
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