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A053858 Squarefree even composite numbers with an odd number of prime factors. 4
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

LINKS

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

EXAMPLE

a(3)=66 because 66 is even and its prime divisors are 2, 3 and 11, an odd number.

MAPLE

ts_m2_sod := proc(n); if (numtheory[mobius](n)=-1 and isprime(n)='false' and type(n, even)='true') then RETURN(n); fi end: am2sod := [seq(ts_m2_sod(i), i=1..2500)]: am2sod;

PROG

(PARI) is(n, f=factor(n))=n%2==0 && #f[, 2]>2 && vecmax(f[, 2])==1 && (#f[, 2])%2 \\ Charles R Greathouse IV, Aug 29 2017

CROSSREFS

A075819 is a subsequence. Intersection of A026424, A039956, and A002808.

Sequence in context: A093599 A007304 A160350 * A075819 A306217 A034683

Adjacent sequences:  A053855 A053856 A053857 * A053859 A053860 A053861

KEYWORD

easy,nonn

AUTHOR

Enoch Haga, Mar 28 2000

EXTENSIONS

Name corrected by Charles R Greathouse IV, Aug 29 2017

STATUS

approved

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Last modified April 20 07:46 EDT 2021. Contains 343125 sequences. (Running on oeis4.)