A171156 -id:A171156 - cp's OEIS frontend

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

Reinhard Zumkeller, Dec 26 2014

nonn

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

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

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

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

A171420 Numbers n such that composite(n)={2 or 3}*{prime > 3}.

Original entry on oeis.org

5, 7, 8, 12, 13, 16, 21, 22, 25, 26, 31, 35, 40, 41, 43, 49, 52, 59, 62, 63, 68, 69, 78, 81, 87, 91, 92, 97, 101, 106, 107, 111, 120, 121, 127, 136, 137, 140, 149, 154, 155, 159, 165, 166, 170, 171, 177, 185, 195, 199, 206, 210, 215, 218, 229, 235, 239, 240, 245

Offset: 1

Juri-Stepan Gerasimov, Dec 08 2009

nonn

Cf. A002808, A171156.

Two missing terms added by D. S. McNeil, Dec 10 2009

cp's OEIS Frontend

A253106 Semiprimes with smallest factor <= 3.

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A171420 Numbers n such that composite(n)={2 or 3}*{prime > 3}.

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