OFFSET
1,1
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
EXAMPLE
k=20 is not a prime; 20 = 2*2*5, largest prime factor is 5 and gcd(5, 20/5) = 1 so 5 is a unitary prime divisor of 20, so 20 is in the sequence.
MATHEMATICA
ma[x_] := Part[Reverse[Flatten[FactorInteger[x]]], 2] k=0; Do[s=ma[n]; If[Equal[GCD[s, n/s], 1]&&!PrimeQ[n], Print[n]], {n, 2, 256}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Feb 21 2003
STATUS
approved