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A075819 Even squarefree numbers with exactly 3 prime factors. 8
30, 42, 66, 70, 78, 102, 110, 114, 130, 138, 154, 170, 174, 182, 186, 190, 222, 230, 238, 246, 258, 266, 282, 286, 290, 310, 318, 322, 354, 366, 370, 374, 402, 406, 410, 418, 426, 430, 434, 438, 442, 470, 474, 494, 498, 506, 518, 530, 534, 574, 582, 590 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

This sequence first differs from A053858 at 2310=2*3*5*7*11, which is in A053858 but not in this sequence.

LINKS

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

EXAMPLE

30=2*3*5 and 42=2*3*7 are even, squarefree and have 3 prime factors.

MAPLE

ts_3_sod := proc(n); if (numtheory[bigomega](n)=3 and numtheory[mobius](n)=-1 and type(n, even)='true') then RETURN(n); fi end: a3sod := [seq(ts_3_sod(i), i=1..2500)]: a3sod;

MATHEMATICA

Select[2*Range[300], SquareFreeQ[#]&&PrimeNu[#]==3&] (* Harvey P. Dale, Feb 16 2018 *)

PROG

(PARI) list(lim)=my(v=List()); forprime(p=5, lim\6, forprime(q=3, min(lim\(2*p), p-2), listput(v, 2*p*q))); Set(v) \\ Charles R Greathouse IV, Aug 29 2017

CROSSREFS

Cf. A053858.

Sequence in context: A007304 A160350 A053858 * A306217 A034683 A328328

Adjacent sequences:  A075816 A075817 A075818 * A075820 A075821 A075822

KEYWORD

easy,nonn

AUTHOR

Jani Melik, Oct 13 2002

EXTENSIONS

Edited by Dean Hickerson, Oct 21 2002

STATUS

approved

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Last modified January 17 20:36 EST 2020. Contains 330987 sequences. (Running on oeis4.)