A253106 Semiprimes with smallest factor <= 3.

4, 6, 9, 10, 14, 15, 21, 22, 26, 33, 34, 38, 39, 46, 51, 57, 58, 62, 69, 74, 82, 86, 87, 93, 94, 106, 111, 118, 122, 123, 129, 134, 141, 142, 146, 158, 159, 166, 177, 178, 183, 194, 201, 202, 206, 213, 214, 218, 219, 226, 237, 249, 254, 262, 267, 274, 278

Offset: 1

Author

Reinhard Zumkeller, Dec 26 2014

Keywords

• nonn

Comments

A253046(a(n)) != a(n).

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. Union of A001748 and A100484, A020639, A010051, A001358, A171156, A253046.

Programs

Haskell

a253106 n = a253106_list !! (n-1)
a253106_list = filter f [1..] where
   f x = p <= 3 && a010051' (div x p) == 1  where p = a020639 x