A065309 - OEIS

%I #19 Dec 18 2024 22:39:01

%S 0,1,3,4,8,8,12,12,12,16,18,20,24,24,24,24,30,30,36,34,32,36,40,42,44,

%T 42,42,40,42,42,56,58,58,56,60,54,60,62,64,66,72,72,82,80,70,68,80,86,

%U 88,80,82,82,84,88,90,90,90,90,96,90,92,100,110,112,102,94,108,110,118

%N a(n) = prime(n) - prime(n - pi(n)).

%H Harry J. Smith, <a href="/A065309/b065309.txt">Table of n, a(n) for n = 1..1000</a>

%F a(n) = A000040(n) - A000040(n - A000720(n)).

%e n=100, prime(100)=541, prime(100 - Pi(100)) = p(75), p(100) - p(75) = 541 - 379 = 162 = a(100).

%t Table[Prime[n]-Prime[n-PrimePi[n]],{n,70}] (* _Harvey P. Dale_, Apr 23 2016 *)

%o (PARI) a(n) = { prime(n) - prime(n - primepi(n)) } \\ _Harry J. Smith_, Oct 16 2009

%Y Cf. A000040, A000720, A065308-A065310.

%K nonn

%O 1,3

%A _Labos Elemer_, Oct 29 2001