A166037 Numbers that are the sum of 2 successive nonprimes A141468.

1, 5, 10, 14, 17, 19, 22, 26, 29, 31, 34, 38, 41, 43, 46, 49, 51, 53, 55, 58, 62, 65, 67, 69, 71, 74, 77, 79, 82, 86, 89, 91, 94, 97, 99, 101, 103, 106, 109, 111, 113, 115, 118, 122, 125, 127, 129, 131, 134, 137, 139, 142, 146, 149, 151, 153, 155, 158, 161, 163, 166

Offset: 1

Author

Juri-Stepan Gerasimov, Oct 05 2009

Keywords

• nonn

Comments

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

Examples

			a(1) = 0 + 1 =  1;
a(2) = 1 + 4 =  5;
a(3) = 4 + 6 = 11.
		

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A001043, A141468.

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

Programs

Maple

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

Mathematica

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