A164376 Nonprime numbers that are not a sum of 2 primes.

0, 1, 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

1,3

Links

G. C. Greubel, Table of n, a(n) for n = 1..1000

Formula

Equals {0,1} union A025583.

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, pn}]; p); Join[{0, 1}, Select[Range[2, 6000], ! PrimeQ[#] && f[#] == 0 &]] (* G. C. Greubel, Sep 18 2017 *)

Crossrefs

Cf. A025583, A141468.

Sequence in context: A141550 A032584 A072492 * A025583 A134101 A226191

Adjacent sequences: A164373 A164374 A164375 * A164377 A164378 A164379

Keyword

nonn

Author

Juri-Stepan Gerasimov, Aug 14 2009

Extensions

Comment turned into formula by R. J. Mathar, Aug 20 2009

Status

approved