A210147 - OEIS

%I #24 Aug 09 2019 12:52:17

%S 7,8,9,11,12,13,15,16,17,19,21,23,24,25,27,28,29,31,33,35,36,37,39,40,

%T 41,43,45,47,48,49,51,53,55,57,59,60,61,63,64,65,67,69,71,73,75,76,77,

%U 79,81,83,84,85,87,88,89,91,93,95,96,97,99,101,103,105,107

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

%C 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]

%e 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.

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

%o (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

%K nonn

%O 1,1

%A _Zak Seidov_, Mar 22 2012