A168255 - OEIS

%I #7 Dec 19 2021 14:00:01

%S 1,2,2,2,2,3,3,3,3,3,3,4,4,4,4,4,4,4,4,5,5,5,5,5,5,5,5,5,6,6,6,6,6,6,

%T 6,6,6,6,7,7,7,7,7,7,7,7,7,7,7,7,8,8,8,8,8,8,8,8,8,8,8,8,8,8,9,9,9,9,

%U 9,9,9,9,9,9,9,9,9,9,9,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10

%N n appears n-th nonprime number times.

%C n appears A018252(n) times.

%H Harvey P. Dale, <a href="/A168255/b168255.txt">Table of n, a(n) for n = 1..1000</a>

%t Module[{nn=20,npn},npn=Select[Range[nn],!PrimeQ[#]&];Table[#[[2]], #[[1]]]&/@ Thread[{npn,Range[Length[npn]]}]]//Flatten (* _Harvey P. Dale_, Dec 19 2021 *)

%K nonn,easy,less

%O 1,2

%A _Jaroslav Krizek_, Nov 21 2009