OFFSET
2,3
COMMENTS
From Reinhard Zumkeller, Jul 08 2010: (Start)
a(n)=0 iff n is not composite;
for composite n: a(n) = max(m: m < n and gcd(m,n) > 1). (End)
LINKS
Antti Karttunen, Table of n, a(n) for n = 2..16385
FORMULA
a(n) = n - A020639(n). - Michel Marcus, Jan 07 2015
MAPLE
MATHEMATICA
Table[n-First@(First/@FactorInteger[n]), {n, 2, 200}] (* Vladimir Joseph Stephan Orlovsky, Apr 08 2011 *)
PROG
(PARI) a(n) = n - factor(n)[1, 1]; \\ Michel Marcus, Jan 07 2015
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved