A368949 Complement of A368087 in A174905.

21, 33, 39, 51, 55, 57, 65, 69, 85, 87, 93, 95, 111, 115, 119, 123, 129, 133, 141, 145, 147, 155, 159, 161, 171, 177, 183, 185, 201, 203, 205, 207, 213, 215, 217, 219, 230, 235, 237, 249, 253, 259, 261, 265, 267, 275, 279, 287, 290, 291, 295, 301, 303, 305, 309, 310, 319, 321, 327, 329, 333, 335, 339, 341

Offset: 1

Author

Hartmut F. W. Hoft, Jan 10 2024

Keywords

• nonn

Comments

A298855 is a subsequence, number 147 = 3 * 7^2 is the first entry in A368949 not in A298855. This sequence is a subsequence of A174905 = A241008 union A241010.

Alternate definition: Every number n in this sequence has at least 2 distinct odd prime factors and its symmetric representation of sigma consists only of parts of width 1.

Examples

			21 is the smallest number in this sequence since 3 * 5 is not in A174905.
The smallest number in this sequence with 3 distinct odd prime factors is 903 = 3*7*43 which has width pattern (A341969) 101010101010101 of length 17 since ... < d_i < 2 * d_i < d_(i+1) < 2 * d_(i+1) ... holds for all its divisors.
		

Crossrefs

Cf. A005279, A174905, A235791, A237048, A237270, A237593, A241008, A241010, A249223, A298855, A341969, A368087.

Programs

Mathematica

(* a174905[ ] is defined in A174905 and propQ[ ] in A368087 *)
a368949[m_, n_] := Select[Range[m, n], a174905[#]&&!propQ[#]&]
a368949[1, 350]