A210147 Numbers expressible as 2*p+q, p and q distinct primes.

7, 8, 9, 11, 12, 13, 15, 16, 17, 19, 21, 23, 24, 25, 27, 28, 29, 31, 33, 35, 36, 37, 39, 40, 41, 43, 45, 47, 48, 49, 51, 53, 55, 57, 59, 60, 61, 63, 64, 65, 67, 69, 71, 73, 75, 76, 77, 79, 81, 83, 84, 85, 87, 88, 89, 91, 93, 95, 96, 97, 99, 101, 103, 105, 107

Offset

1,1

Comments

Odd terms are of the form 4+p (p odd prime), even terms are of the form 2+2*p (p odd prime). [No: the odd term 13 =4+9 is not of that form, nor 19=4+15; see A175221 for others. - R. J. Mathar, Aug 09 2019]

Links

Table of n, a(n) for n=1..65.

Example

7=2*2+3, 8=2+2*3, 9=2*2+5, 11=2*2+7, 12=2+2*5, 13=2*3+7=2*5+3; 19=2*3+13=2*7+5 etc.

Mathematica

Union[Flatten[{2#[[1]]+#[[2]], #[[1]]+2#[[2]]}&/@Subsets[Prime[Range[20]], {2}]]] (* Harvey P. Dale, Apr 01 2013 *)

Prog

(PARI) list(lim)=my(v=[], u); forprime(p=2, lim\2-1, u=List(); forprime(q=2, lim-2*p, if(p!=q, listput(u, 2*p+q))); v=vecsort(concat(v, Vec(u)), , 8)); v \\ Charles R Greathouse IV, Mar 22 2012

Crossrefs

Sequence in context: A120309 A035705 A205698 * A340741 A097338 A196040

Adjacent sequences: A210144 A210145 A210146 * A210148 A210149 A210150

Keyword

nonn

Author

Zak Seidov, Mar 22 2012

Status

approved