

A215567


Numbers n with property that n and the nth number which is a product of n primes have the largest prime divisor and with the same multiplicity.


0



3, 13, 20, 42, 44, 45, 56, 60, 86, 87, 112, 119, 121
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OFFSET

1,1


LINKS

Table of n, a(n) for n=1..13.


EXAMPLE

a(2) = 13 because n = 13 and 13th 13almost prime = 13*2^12 = 53248 has same largest prime factor = 13.


MATHEMATICA

AlmostPrimePi[k_Integer, n_]:=...; AlmostPrime[k_, n_]:=...;
fQ[n_]:=FactorInteger[n][[1, 1]]==FactorInteger[AlmostPrime[n, n]][[1, 1]]; k=1; lst={};
While[k<150, If[fQ@k, AppendTo[lst, k]; Print@k]; k++]; lst (* Robert G. Wilson v, Aug 27 2012 *)


CROSSREFS

Cf. A001222, A101695, A215405.
Sequence in context: A271924 A178712 A273686 * A214519 A099502 A145024
Adjacent sequences: A215564 A215565 A215566 * A215568 A215569 A215570


KEYWORD

nonn,less


AUTHOR

JuriStepan Gerasimov, Aug 16 2012


EXTENSIONS

a(9)a(13) from Robert G. Wilson v, Aug 27 2012
Definition clarified by N. J. A. Sloane, Sep 04 2012


STATUS

approved



