A071965 Numbers k such that k = Gpf(k) * Gpf(sigma(k)) where Gpf(k) = A006530(k) is the greatest prime factor of k.

15, 33, 51, 69, 91, 95, 141, 145, 159, 213, 287, 295, 321, 395, 445, 473, 573, 581, 679, 703, 745, 895, 973, 995, 1139, 1149, 1169, 1195, 1199, 1293, 1339, 1345, 1441, 1561, 1717, 1757, 1795, 1891, 1941, 2051, 2147, 2167, 2245, 2353, 2395, 2443, 2495, 2589

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Mathematica

Select[Range[2, 3000], FactorInteger[#][[-1, 1]]FactorInteger[ DivisorSigma[ 1, #]] [[-1, 1]]==#&] (* Harvey P. Dale, Sep 15 2011 *)

Prog

(PARI) for(n=1, 3000, if(vecmax(component(factor(n), 1))*vecmax(component(factor(sigma(n)), 1))==n, print1(n, ", ")))

Crossrefs

Cf. A000203, A006530, A071190.

Sequence in context: A190754 A357934 A327900 * A242677 A020184 A231371

Adjacent sequences: A071962 A071963 A071964 * A071966 A071967 A071968

Keyword

easy,nonn

Author

Benoit Cloitre, Jun 16 2002

Status

approved