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A175668 First differences of A175648. 1

%I

%S 4,11,1,12,1,16,7,7,17,5,4,20,4,3,1,10,12,1,13,28,18,1,3,4,4,1,1,2,32,

%T 25,13,4,4,3,1,2,4,14,4,12,23,3,16,5,9,3,9,4,4,2,34,7,15,9,3,4,4,4,4,

%U 4,10,4,14,4,5,24,17,43,7,38,14,4,9,1,4,4,10,4,28,4,14,4,14,4,4,10,4,10

%N First differences of A175648.

%C Distance between twin semiprime pairs.

%p A175648 := proc(n) option remember; if n = 1 then 6; else for a from procname(n-1)+1 do if numtheory[bigomega](a) = 2 and numtheory[bigomega](a+4) = 2 then return a; end if; end do: end if; end proc:

%p A175668 := proc(n) A175648(n+1)-A175648(n) ; end proc:

%p seq(A175668(n),n=1..100) ; # _R. J. Mathar_, Aug 07 2010

%Y Cf. A053319, A175612, A175648.

%K nonn

%O 1,1

%A _Juri-Stepan Gerasimov_, Aug 05 2010

%E Terms from a(33) on corrected by _R. J. Mathar_, Aug 07 2010

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Last modified May 13 05:02 EDT 2021. Contains 343836 sequences. (Running on oeis4.)