

A181447


Numbers n such that 3 is the largest prime factor of n^2  1.


29




OFFSET

1,1


COMMENTS

Sequence is finite and complete, for proof see A175607.
Search for terms can be restricted to the range from 2 to A175607(2) = 17; primepi(3) = 2.


LINKS

Table of n, a(n) for n=1..4.


MATHEMATICA

Select[Range[20], FactorInteger[#^21][[1, 1]]==3&]


PROG

(MAGMA) [ n: n in [2..20]  m eq 3 where m is D[#D] where D is PrimeDivisors(n^21) ]; // Klaus Brockhaus, Feb 17 2011
(PARI) is(n)=n=n^21; my(o=valuation(n, 3)); o && n>>valuation(n/3^o, 2)==1 \\ Charles R Greathouse IV, Jul 01 2013


CROSSREFS

Cf. A175607, A181448A181470, A181568.
Sequence in context: A322440 A067580 A325210 * A082088 A075881 A208241
Adjacent sequences: A181444 A181445 A181446 * A181448 A181449 A181450


KEYWORD

nonn,fini,full


AUTHOR

Artur Jasinski, Oct 21 2010


STATUS

approved



