A334146 Numbers with at least two prime factors greater than 3 counted with multiplicity.

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

Links

Table of n, a(n) for n=1..55.

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

Adjacent sequences: A334143 A334144 A334145 * A334147 A334148 A334149

Keyword

nonn,easy

Author

Aidan Clarke, Apr 16 2020

Status

approved