OFFSET
1,1
COMMENTS
If k = p(1)*p(2)*...p(r) is in the sequence, where p(r) is the largest prime factor, then p(r) = p(1)+p(2)+...+p(r-1).
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
EXAMPLE
20706 = 2*3*7*17*29 and 2+3+7+17 = 29 hence 20706 is in the sequence.
MATHEMATICA
Select[Range[40000], SquareFreeQ[#] && Plus @@ (f = FactorInteger[#][[;; , 1]]) == 2 * f[[-1]] &] (* Amiram Eldar, Apr 23 2022 *)
PROG
(PARI) for(n=2, 100000, if(issquarefree(n)*sum(i=1, omega(n)-1, component(component(factor(n), 1), i))==vecmax(factor(n, 1)), print1(n, ", ")))
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Benoit Cloitre, Jun 11 2002
STATUS
approved