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A279456 Numbers n such that number of distinct primes dividing n is odd and number of prime divisors (counted with multiplicity) of n is even. 4
4, 9, 16, 25, 49, 60, 64, 81, 84, 90, 121, 126, 132, 140, 150, 156, 169, 198, 204, 220, 228, 234, 240, 256, 260, 276, 289, 294, 306, 308, 315, 336, 340, 342, 348, 350, 360, 361, 364, 372, 380, 414, 444, 460, 476, 490, 492, 495, 504, 516, 522, 525, 528, 529, 532, 540, 550, 558, 560, 564, 572, 580, 585, 600 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Intersection of A028260 and A030230.
Numbers n such that A000035(A001221(n)) = 1 and A000035(A001222(n)) = 0.
Numbers n such that A076479(n) = -1 and A008836(n) = 1.
LINKS
Eric Weisstein's World of Mathematics, Prime Factor
Eric Weisstein's World of Mathematics, Distinct Prime Factors
EXAMPLE
90 is in the sequence because 90 = 2*3^2*5 therefore omega(90) = 3 {2,3,5} is odd and bigomega(90) = 4 {2,3,3,5} is even.
MATHEMATICA
Select[Range[600], Mod[PrimeNu[#1], 2] == 1 && Mod[PrimeOmega[#1], 2] == 0 & ]
CROSSREFS
Sequence in context: A108612 A065741 A188061 * A069560 A075494 A063735
KEYWORD
nonn,easy
AUTHOR
Ilya Gutkovskiy, Dec 12 2016
STATUS
approved

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Last modified April 14 03:22 EDT 2024. Contains 371652 sequences. (Running on oeis4.)