|
%I #12 Sep 08 2022 08:46:18
%S 0,1,2,3,3,4,4,5,6,7,7,8,9,10,10,11,12,13,14,15,16,17,17,18,19,20,20,
%T 21,22,23,24,25,26,27,27,28,29,30,30,31,32,33,34,35,36,37,37,38,39,40,
%U 41,42,43,44,45,46,47,48,48,49,50,51,51,52,53,54,55,56,57,58,59,60,61,62,62,63,64,65,66,67,68
%N a(n) = n - pi(n/2).
%H Vincenzo Librandi, <a href="/A282029/b282029.txt">Table of n, a(n) for n = 0..10000</a>
%t Table[n - PrimePi[n/2], {n, 0, 100}] (* _Vincenzo Librandi_, Feb 18 2017 *)
%o (Magma) [0,1] cat [ n-#PrimesUpTo(n div 2): n in [2..90] ]; // _Vincenzo Librandi_, Feb 18 2017
%o (PARI) a(n)=n - primepi(n\2) \\ _Charles R Greathouse IV_, Feb 18 2017
%Y Cf. A000720, A282028.
%K nonn
%O 0,3
%A _N. J. A. Sloane_, Feb 17 2017
|
