A230213 Odious numbers (A000069) which can be written as a product of two evil numbers (A001969).

25, 50, 69, 81, 87, 100, 115, 117, 138, 145, 162, 171, 174, 200, 213, 230, 234, 261, 265, 276, 285, 289, 290, 324, 333, 339, 342, 345, 348, 351, 355, 357, 369, 375, 385, 391, 400, 405, 415, 425, 426, 445, 460, 468, 475, 477, 493, 505, 522, 529, 530, 552, 555

Offset: 1

Author

Vladimir Shevelev, Oct 11 2013

Keywords

• nonn
• base

Examples

			Odious number 100 equals 5*20, such that 5 and 20 are evil. So, 100 is in the sequence.
		

Links

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

Crossrefs

Cf. A000069, A001969.

Programs

Mathematica

evilQ[n_] := EvenQ[DigitCount[n, 2][[1]]]; 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] && ! (evilQ[f[[i]]] && evilQ[n/f[[i]]]), i++]; i <= Length[f]]]; Select[Range[1000], odiousQ[#] && fQ[#] &] (* T. D. Noe, Oct 16 2013 *)

Extensions

Extended by T. D. Noe, Oct 16 2013