A142728 - OEIS

%I #14 Oct 01 2024 23:18:53

%S 0,1,1,35,35,39,45,45,49,75,77,81,95,105,115,119,143,145,147,159,187,

%T 187,207,217,219,235,235,243,249,267,273,289,321,325,335,339,361,365,

%U 369,369,381,381,395,395,411,411,417,427,441,459,465,471,471,485,485

%N Nonprimes of the form (p(n)-2*n)/3, where p(n)=n-th prime.

%H Harvey P. Dale, <a href="/A142728/b142728.txt">Table of n, a(n) for n = 1..1000</a>

%e If n=1, then (p(1)-2*1)/3=(2-2)/3=0=a(1).

%e If n=7, then (p(7)-2*7)/3=(17-14)/3=1=a(2).

%e If n=8, then (p(8)-2*8)/3=(19-16)/3=1=a(3).

%e If n=43, then (p(43)-2*43)/3=(191-86)/3=35=a(4), etc.

%t Select[Table[(Prime[n]-2n)/3,{n,0,500}],IntegerQ[#]&&!PrimeQ[#]&] (* _Harvey P. Dale_, Oct 18 2023 *)

%Y Cf. A000040, A141468.

%K nonn,changed

%O 1,4

%A _Juri-Stepan Gerasimov_, Oct 07 2008

%E Corrected (29 replaced by double-35, 39 and 45, 115 inserted, 145 inserted, 338 replaced by 339 etc.) - _R. J. Mathar_, Apr 18 2010