login
n-th prime plus n-th even nonnegative nonprime.
3

%I #5 Mar 30 2012 18:52:39

%S 2,7,11,15,21,25,31,35,41,49,53,61,67,71,77,85,93,97,105,111,115,123,

%T 129,137,147,153,157,163,167,173,189,195,203,207,219,223,231,239,245,

%U 253,261,265,277,281,287,291,305,319,325,329,335,343,347,359,367,375

%N n-th prime plus n-th even nonnegative nonprime.

%C Apart from the first term, same as A078916 = prime(n) + 2n.

%F a(n)=A000040(n)+A163300(n).

%F a(n) ~ n log n.

%e a(1)=2 because 2+0=2; a(2)=7 because 3+4=7.

%p Contribution from _R. J. Mathar_, Apr 14 2010: (Start)

%p A163300 := proc(n) option remember ; if n = 1 then 0; else for a from procname(n-1)+2 by 2 do if not isprime(a) then return a ; end if; end do; end if; end proc:

%p A174008 := proc(n) ithprime(n)+A163300(n) ; end proc: seq(A174008(n),n=1..80) ; (End)

%Y Cf. A000040, A001477, A078916, A163300.

%K nonn,easy,less

%O 1,1

%A _Juri-Stepan Gerasimov_, Mar 05 2010