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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. 9
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

Andrew Howroyd, Table of n, a(n) for n = 1..300

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

Cf. A001222, A007916, A055932, A056239, A124010, A133808, A242414, A296150.

Cf. A317087, A317088, A317090, A317091, A317092.

Sequence in context: A113274 A181660 A036913 * A117311 A125024 A178480

Adjacent sequences:  A317086 A317087 A317088 * A317090 A317091 A317092

KEYWORD

nonn

AUTHOR

Gus Wiseman, Jul 21 2018

STATUS

approved

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Last modified April 22 04:04 EDT 2019. Contains 322329 sequences. (Running on oeis4.)