A166037 - OEIS

%I #19 May 05 2019 04:01:17

%S 1,5,10,14,17,19,22,26,29,31,34,38,41,43,46,49,51,53,55,58,62,65,67,

%T 69,71,74,77,79,82,86,89,91,94,97,99,101,103,106,109,111,113,115,118,

%U 122,125,127,129,131,134,137,139,142,146,149,151,153,155,158,161,163,166

%N Numbers that are the sum of 2 successive nonprimes A141468.

%C a(n) = (n-1)-th nonprimes + (n-1)-th composites for n >= 2. a(n) = A018252(n-1) + A002808(n-1) for n >= 2. - _Jaroslav Krizek_, Dec 13 2009

%H Harvey P. Dale, <a href="/A166037/b166037.txt">Table of n, a(n) for n = 1..10000</a>

%e a(1) = 0 + 1 =  1;

%e a(2) = 1 + 4 =  5;

%e a(3) = 4 + 6 = 11.

%p A002808 := proc(n) option remember; if n = 1 then 4; else for a from procname(n-1)+1 do if not isprime(a) then return a; fi; od: fi; end: A141468 := proc(n) if n <= 2 then n-1 ; else A002808(n-2) ; fi; end: A166037 := proc(n) A141468(n)+A141468(n+1) ; end: seq(A166037(n),n=1..120) ; # _R. J. Mathar_, Oct 10 2009

%t With[{nn=100},Join[{1},Total/@Partition[Complement[Range[nn],Prime[ Range[ PrimePi[ nn]]]],2,1]]] (* _Harvey P. Dale_, Aug 03 2014 *)

%Y Cf. A001043, A141468.

%Y Cf. A167915 (primes that are the sums of two consecutive composites).

%K nonn

%O 1,2

%A _Juri-Stepan Gerasimov_, Oct 05 2009