A335650 Numbers that are multiples of 2,3,5, or 7 but not multiples of the product of any combination of 2,3,5, and 7.

2, 3, 4, 5, 7, 8, 9, 16, 22, 25, 26, 27, 32, 33, 34, 38, 39, 44, 46, 49, 51, 52, 55, 57, 58, 62, 64, 65, 68, 69, 74, 76, 77, 81, 82, 85, 86, 87, 88, 91, 92, 93, 94, 95, 99, 104, 106, 111, 115, 116, 117, 118, 119, 122, 123, 124, 125, 128, 129, 133, 134, 136, 141, 142

Offset

1,1

Links

Table of n, a(n) for n=1..64.

Example

4 is a term because 4 = 2 * 2;
77 is a term because 77 = 7 * 11;
6 is not a term because 6 = 2 * 3;
21 is not a term because 21 = 3 * 7;
30 is not a term because 30 = 2 * 3 * 5;
210 is not a term because 210 = 2 * 3 * 5 * 7.

Maple

q:= n-> is(igcd(n, 210) in {2, 3, 5, 7}):
select(q, [$0..200])[];  # Alois P. Heinz, Jun 16 2020

Mathematica

Select[Range[150], Count[IntegerExponent[#, {2, 3, 5, 7}], 0] == 3 &] (* Amiram Eldar, Jun 16 2020 *)

Prog

(Haskell) a335650 = [x | x <- [0..], (gcd x 210) `elem` [2, 3, 5, 7]]

Crossrefs

Cf. A126590.

Sequence in context: A107684 A111796 A039124 * A056759 A101511 A111747

Adjacent sequences: A335647 A335648 A335649 * A335651 A335652 A335653

Keyword

nonn

Author

Peter Andrew, Jun 15 2020

Status

approved