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A189314 Nonprimes k such that 2*omega(4k) = omega(4k+2), where omega(j) is the number of distinct primes dividing j, A001221. 2
1, 4, 8, 52, 82, 128, 136, 142, 172, 178, 192, 214, 232, 262, 292, 304, 332, 346, 352, 382, 388, 412, 448, 472, 478, 484, 500, 502, 542, 556, 586, 592, 604, 622, 632, 640, 652, 676, 712, 724, 752, 766, 772, 802, 808, 832, 838, 841, 862, 864, 916, 922, 934 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Nathaniel Johnston, Table of n, a(n) for n = 1..10000

MAPLE

Omega:=proc(n)return nops(factorset(n)):end:for n from 1 to 1000 do

if(not isprime(n) and 2*Omega(4*n)=Omega(4*n+2))then printf("%d, ", n); fi:od: # Nathaniel Johnston, Apr 19 2011

MATHEMATICA

Select[Range[1000], ! PrimeQ[#] && 2*PrimeNu[4 #] == PrimeNu[4 # + 2] &] (* T. D. Noe, Apr 21 2011 *)

CROSSREFS

Cf. A189313 (prime version of this sequence).

Sequence in context: A267987 A056407 A056397 * A215746 A128893 A214603

Adjacent sequences:  A189311 A189312 A189313 * A189315 A189316 A189317

KEYWORD

nonn

AUTHOR

Juri-Stepan Gerasimov, Apr 19 2011

STATUS

approved

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Last modified July 18 19:00 EDT 2019. Contains 325144 sequences. (Running on oeis4.)