cp's OEIS Frontend

A213386 Smallest number k such that the sum of the distinct prime divisors of k equals n times a square > 1.

%I A213386 #7 Jun 25 2012 06:07:57
%S A213386 14,15,35,39,51,95,115,87,155,111,123,215,235,159,371,183,302,335,219,
%T A213386 511,395,415,267,623,291,303,482,327,339,791,554,1415,635,655,411,695,
%U A213386 662,447,698,471,734,815,835,519,1211,543,842,1991,579,591,914,2167
%N A213386 Smallest number k such that the sum of the distinct prime divisors of k equals n times a square > 1.
%C A213386 Smallest k such that sopf(k) = n*q where q is a square.
%H A213386 Michel Lagneau, <a href="/A213386/b213386.txt">Table of n, a(n) for n = 1..1000</a>
%e A213386 a(55) = 2631 because 2631 = 3*877 and 3 + 877 = 880 = 55*16 where 16 is a square.
%p A213386 with (numtheory):
%p A213386 sopf:= proc(n) option remember;
%p A213386 add(i, i=factorset(n))
%p A213386 end:
%p A213386 a:= proc(n) local k, p;
%p A213386 for k from 2 while irem(sopf(k), n, 'p')>0 or
%p A213386 sqrt(p)<>floor(sqrt(p)) or p=1 do od; k
%p A213386 end:
%p A213386 seq (a(n), n=1..100);
%Y A213386 Cf. A008492, A213420.
%K A213386 nonn
%O A213386 1,1
%A A213386 _Michel Lagneau_, Jun 10 2012