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A175648 Semiprimes m such that m+4 is also semiprime. 10

%I #26 Dec 09 2015 10:15:35

%S 6,10,21,22,34,35,51,58,65,82,87,91,111,115,118,119,129,141,142,155,

%T 183,201,202,205,209,213,214,215,217,249,274,287,291,295,298,299,301,

%U 305,319,323,335,358,361,377,382,391,394,403,407,411,413,447,454,469,478

%N Semiprimes m such that m+4 is also semiprime.

%H Zak Seidov, <a href="/A175648/b175648.txt">Table of n, a(n) for n = 1..10000</a>

%p select(t -> numtheory:-bigomega(t)=2 and numtheory:-bigomega(t+4)=2, [$1..1000]); # _Robert Israel_, Feb 12 2015

%t Select[Range@ 480, And[PrimeOmega@ # == 2, PrimeOmega[# + 4] == 2] &] (* _Michael De Vlieger_, Dec 09 2015 *)

%o (PARI) isok(n) = (bigomega(n) == 2) && (bigomega(n+4) == 2); \\ _Michel Marcus_, Feb 12 2015

%Y Cf. A001358, A001359, A175612.

%K nonn,easy

%O 1,1

%A _Juri-Stepan Gerasimov_, Aug 02 2010

%E Corrected (309 removed) by _R. J. Mathar_, Aug 03 2010

%E Definition corrected by _Zak Seidov_, Feb 12 2015

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Last modified March 28 09:04 EDT 2024. Contains 371240 sequences. (Running on oeis4.)