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A317089 Numbers whose prime factors span an initial interval of prime numbers and whose prime multiplicities span an initial interval of positive integers. 19
2, 6, 12, 18, 30, 60, 90, 150, 180, 210, 300, 360, 420, 450, 540, 600, 630, 1050, 1260, 1350, 1470, 1500, 2100, 2250, 2310, 2520, 2940, 3150, 3780, 4200, 4410, 4620, 5880, 6300, 6930, 7350, 8820, 9450, 10500, 11550, 12600, 13230, 13860, 14700, 15750, 16170 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
EXAMPLE
The sequence of rows of A296150 indexed by the terms of this sequence begins: (1), (21), (211), (221), (321), (3211), (3221), (3321), (32211), (4321), (33211), (322111), (43211).
MATHEMATICA
normalQ[m_]:=Union[m]==Range[Max[m]];
Select[Range[10000], And[normalQ[PrimePi/@FactorInteger[#][[All, 1]]], normalQ[FactorInteger[#][[All, 2]]]]&]
PROG
(PARI) ok(n)={my(f=factor(n), p=f[, 1], e=vecsort(f[, 2], , 8)); n > 1 && #p==primepi(p[#p]) && #e==e[#e]} \\ Andrew Howroyd, Aug 26 2018
CROSSREFS
Sequence in context: A113274 A181660 A036913 * A117311 A125024 A178480
KEYWORD
nonn
AUTHOR
Gus Wiseman, Jul 21 2018
STATUS
approved

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Last modified March 2 21:08 EST 2024. Contains 370498 sequences. (Running on oeis4.)