A109934 Composite numbers which are not the sum of two distinct primes.

4, 6, 27, 35, 51, 57, 65, 77, 87, 93, 95, 117, 119, 121, 123, 125, 135, 143, 145, 147, 155, 161, 171, 177, 185, 187, 189, 203, 205, 207, 209, 215, 217, 219, 221, 237, 245, 247, 249, 255, 261, 267, 275, 287, 289, 291, 297, 299, 301, 303, 305, 321, 323, 325, 327

Offset: 1

Author

Amarnath Murthy, Jul 19 2005

Keywords

• nonn

Comments

Perhaps there are no even terms > 6.

Links

• T. D. Noe, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A025583.

Programs

Mathematica

f[n_] := (p = 0; pn = PrimePi[n];
Do[ If[n == Prime[i] + Prime[k], p = p + 1; If[p > 2, Break[]]], {i, 1, pn},
{k, i+1, pn}]; p );
Select[Range[2, 400], ! PrimeQ[#] && f[#] == 0 & ] (* Jean-François Alcover, Mar 07 2011 *)