|
%I #24 Dec 07 2019 12:18:24
%S 1,2,3,4,4,5,6,6,7,8,8,9,9,9,10,11,11,11,12,12,13,14,14,15,15,15,16,
%T 16,16,17,18,18,18,19,19,20,21,21,21,22,22,23,23,23,24,24,24,24,25,25,
%U 26,27,27,28,29,29,30,30,30,30,30,30,30,31,31,32,32,32,33,34,34,34,34,34
%N Bisection of A000720.
%C Maximal number of primes possible in a string of 2n consecutive numbers. - _Lekraj Beedassy_, Dec 04 2004
%C a(n) = A139325(n,1) + 1. - _Reinhard Zumkeller_, Apr 14 2008
%C Or the number of primes <= 2n. - _Juri-Stepan Gerasimov_, Oct 29 2009
%F a(n) = A000720(n) + A035250(n) - A010051(n). - _Reinhard Zumkeller_, Jul 05 2010
%F a(n) = A000720(2*n). - _Wesley Ivan Hurt_, Jun 16 2013
%p with(numtheory):seq(pi(2*n),n=1..86); # _Emeric Deutsch_, Apr 12 2005
%o (Sage) [prime_pi(2*n) for n in range(1, 75)] # _Zerinvary Lajos_, Jun 06 2009
%o (PARI) a(n)=primepi(2*n) \\ _Charles R Greathouse IV_, Sep 02 2015
%Y Cf. A099081.
%K nonn,easy
%O 1,2
%A _N. J. A. Sloane_, Nov 19 2004
%E More terms from _Emeric Deutsch_, Apr 12 2005
|
