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A334146
Numbers with at least two prime factors greater than 3 counted with multiplicity.
0
25, 35, 49, 50, 55, 65, 70, 75, 77, 85, 91, 95, 98, 100, 105, 110, 115, 119, 121, 125, 130, 133, 140, 143, 145, 147, 150, 154, 155, 161, 165, 169, 170, 175, 182, 185, 187, 190, 195, 196, 200, 203, 205, 209, 210, 215, 217, 220, 221, 225, 230, 231, 235, 238, 242
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
Cf. A093641.
Sequence in context: A061442 A049514 A049518 * A133633 A038509 A067793
KEYWORD
nonn,easy
AUTHOR
Aidan Clarke, Apr 16 2020
STATUS
approved