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

1,1

Links

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

Example

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

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 *)

Crossrefs

Cf. A000069, A001969.

Sequence in context: A118882 A085625 A116490 * A338890 A008607 A044077

Adjacent sequences: A230210 A230211 A230212 * A230214 A230215 A230216

Keyword

nonn,base

Author

Vladimir Shevelev, Oct 11 2013

Extensions

Extended by T. D. Noe, Oct 16 2013

Status

approved