A088752 - OEIS

%I #9 Nov 19 2017 19:09:58

%S 1,4,3,4,4,5,6,6,6,7,7,8,9,9,8,9,9,10,11,12,11,12,13,14,14,15,14,15,

%T 15,16,17,18,18,19,18,19,20,21,20,21,21,22,23,24,23,24,25,26,26,27,26,

%U 27,28,29,29,30,29,30,30,31,32,33,33,34,33,34,35,36,35,36,36,37,38,39,39

%N Let CompositePi(n) = number of composite numbers <= n and PrimePi(n) = number of primes <= n, so that CompositePi(n) + PrimePi(n) = n. Then a(n) = floor(n*(n - PrimePi(n))/(n-1-PrimePi(n-1) + n - 2 - PrimePi(n-2))).

%t digits=200 a=Table[Floor[n*(n-PrimePi[n])/(n-1-PrimePi[n-1]+n-2-PrimePi[n-2])], {n, 3, digits}]

%K nonn

%O 3,2

%A _Roger L. Bagula_, Oct 14 2003