OFFSET
1,1
FORMULA
a(n) ~ n. - Charles R Greathouse IV, Apr 16 2020
EXAMPLE
25 = 5*5
35 = 5*7
49 = 7*7
50 = (2)*5*5
55 = 5*11
65 = 5*13
70 = (2)*5*7
75 = (3)*5*5
MATHEMATICA
Select[Range[250], CompositeQ[# / 2^IntegerExponent[#, 2] / 3^IntegerExponent[#, 3]] &] (* Amiram Eldar, May 01 2020 *)
PROG
(PARI) is(n)=n>>=valuation(n, 2); n/=3^valuation(n, 3); n>1 && !isprime(n) \\ Charles R Greathouse IV, Apr 16 2020
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Aidan Clarke, Apr 16 2020
STATUS
approved