A230226 Odd odious numbers (A000069) which can be written as a product of two odious numbers > 1.

49, 91, 121, 133, 143, 217, 247, 259, 273, 341, 361, 385, 403, 451, 475, 481, 511, 517, 539, 589, 611, 625, 637, 651, 665, 671, 721, 737, 749, 767, 775, 779, 793, 803, 805, 847, 861, 871, 875, 889, 925, 949, 959, 961, 1001, 1015, 1027, 1029, 1053, 1057, 1067

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Example

From Bernard Schott, Sep 23 2019: (Start)
49 = 7 * 7 with 7 = 111_2 and 49 = 110001_2 hence 49 is a term.
91 = 7 * 13 with 7 = 111_2, 13 = 1101_2 and 91 = 1011011_2, hence 91 is a term. (End)

Mathematica

odiousQ[n_] := OddQ[DigitCount[n, 2][[1]]]; fQ[n_] := Module[{f, i}, If[PrimeQ[n], False, f = Select[Divisors[n], # > 1 && # <= Sqrt[n] &]; i = 1; While[i <= Length[f] && ! (odiousQ[f[[i]]] && odiousQ[n/f[[i]]]), i++]; i <= Length[f]]]; Select[Range[1, 1000, 2], odiousQ[#] && fQ[#] &] (* T. D. Noe, Oct 16 2013 *)

Crossrefs

Cf. A000069, A230213.

Sequence in context: A090825 A350704 A157342 * A178705 A118886 A198773

Adjacent sequences: A230223 A230224 A230225 * A230227 A230228 A230229

Keyword

nonn,base

Author

Vladimir Shevelev, Oct 12 2013

Extensions

Extended by T. D. Noe, Oct 16 2013

Status

approved