

A067187


Numbers that can be expressed as the sum of two primes in exactly one way.


10



4, 5, 6, 7, 8, 9, 12, 13, 15, 19, 21, 25, 31, 33, 39, 43, 45, 49, 55, 61, 63, 69, 73, 75, 81, 85, 91, 99, 103, 105, 109, 111, 115, 129, 133, 139, 141, 151, 153, 159, 165, 169, 175, 181, 183, 193, 195, 199, 201, 213, 225, 229, 231, 235, 241, 243, 253, 259, 265, 271
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OFFSET

1,1


COMMENTS

All primes + 2 are terms of this sequence. Is 12 the last even term?  Frank Ellermann, Jan 17 2002
A048974, A052147, A067187 and A088685 are very similar after dropping terms less than 13.  Eric W. Weisstein, Oct 10 2003
Values of n such that A061358(n)=1.  Emeric Deutsch, Apr 03 2006


LINKS

Table of n, a(n) for n=1..60.
Index entries for sequences related to Goldbach conjecture


EXAMPLE

4 is a term as 4 = 2+2, 15 is a term as 15 = 13+2.


MAPLE

g:=sum(sum(x^(ithprime(i)+ithprime(j)), i=1..j), j=1..80): gser:=series(g, x=0, 280): a:=proc(n) if coeff(gser, x^n)=1 then n else fi end: seq(a(n), n=1..272); # Emeric Deutsch, Apr 03 2006


MATHEMATICA

cQ[n_]:=Module[{c=0}, Do[If[PrimeQ[ni]&&PrimeQ[i], c++], {i, 2, n/2}]; c==1]; Select[Range[4, 271], cQ[#]&] (* Jayanta Basu, May 22 2013 *)


CROSSREFS

Cf. A023036, A067188A067191, A066722, A045917, A061358.
Subsequence of A014091.
Cf. A061358.
Sequence in context: A321025 A047569 A039062 * A321353 A161674 A285623
Adjacent sequences: A067184 A067185 A067186 * A067188 A067189 A067190


KEYWORD

nonn


AUTHOR

Amarnath Murthy, Jan 10 2002


EXTENSIONS

Edited by Frank Ellermann, Jan 17 2002


STATUS

approved



