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Number of twin primes < 2^n.
3

%I #16 Feb 07 2024 09:02:34

%S 0,1,2,3,5,7,10,17,24,36,62,107,177,290,505,860,1526,2679,4750,8535,

%T 15500,27995,50638,92246,168617,309561,571313,1056281,1961080,3650557,

%U 6810670,12739574,23878645,44849427,84384508,159082253,300424743,568237005,1076431099,2042054332,3879202049

%N Number of twin primes < 2^n.

%C For n=2 only the lower member of the pair [3,5] is < 2^n. - _Hugo Pfoertner_, Feb 07 2024

%H <a href="/index/Pri#primepop">Index entries for sequences related to numbers of primes in various ranges</a>

%Y Cf. A007053, A007508.

%Y Partial sums of A095017.

%K nonn,hard

%O 1,3

%A Vasiliy Danilov (danilovv(AT)usa.net), Jun 15 1998

%E a(38) from _Alex Ratushnyak_, Jun 07 2013

%E a(39)-a(41) from _Hugo Pfoertner_, Feb 07 2024