A123666 Numbers with an even number of prime factors, at least half of which are 2.

1, 4, 6, 10, 14, 16, 22, 24, 26, 34, 36, 38, 40, 46, 56, 58, 60, 62, 64, 74, 82, 84, 86, 88, 94, 96, 100, 104, 106, 118, 122, 132, 134, 136, 140, 142, 144, 146, 152, 156, 158, 160, 166, 178, 184, 194, 196, 202, 204, 206, 214, 216, 218, 220, 224, 226, 228, 232, 240

Offset

1,2

Comments

This is the lexicographically earliest maximal set of nonprime integers that has unique factorization. Products of any number of terms from A100484, with repetition allowed.

Links

James C. McMahon, Table of n, a(n) for n = 1..10000

Mathematica

fn[b_]:=Total[Last/@FactorInteger[b]]; Join[{1}, Select[Range[240], EvenQ[#]&&EvenQ[fn[#]]&&First[FactorInteger[#]][[2]]>=fn[#]/2&]] (* James C. McMahon, Nov 23 2024 *)

Crossrefs

Cf. A100484, A002808, A123667.

Sequence in context: A298784 A241975 A063745 * A095305 A362416 A058917

Adjacent sequences: A123663 A123664 A123665 * A123667 A123668 A123669

Keyword

nonn

Author

Franklin T. Adams-Watters, Oct 04 2006

Status

approved