A238367 Even numbers n such that n is not divisible by 2^d where d is the number of distinct odd prime factors of n.

30, 42, 66, 70, 78, 90, 102, 110, 114, 126, 130, 138, 150, 154, 170, 174, 182, 186, 190, 198, 210, 222, 230, 234, 238, 246, 258, 266, 270, 282, 286, 290, 294, 306, 310, 318, 322, 330, 342, 350, 354, 366, 370, 374, 378, 390, 402, 406, 410, 414, 418, 420, 426, 430, 434, 438, 442, 450, 462, 470, 474, 490, 494, 498

Offset: 1

Author

Robert G. Wilson v, Feb 25 2014

Keywords

• nonn

Comments

Inspired by comment by Don Reble in A072995.

2*A061346 = A238367 with the exceptions of 420, 660, 780, 924, 1020, 1092, 1140, 1260, ... .

Examples

			30 is in the sequence because the odd primes that divide 30 are 3 and 5, but 2^2 does not divide 30.
		

Crossrefs

Cf. A072995.

Programs

Mathematica

Select[2 Range[250], Mod[#, 2^(PrimeNu[#] - 1)] != 0 &]