A228490 Numbers k for which prime(1) + ... + prime(k) = 2*prime(m) for some m.

3, 7, 55, 59, 65, 75, 93, 133, 137, 141, 249, 277, 313, 365, 375, 387, 391, 435, 471, 499, 563, 573, 597, 605, 619, 645, 675, 719, 787, 797, 799, 815, 825, 845, 867, 879, 919, 937, 957, 971, 1011, 1013, 1145, 1217, 1225, 1243, 1251, 1271, 1283, 1311, 1373

Offset: 1

Author

Clark Kimberling, Oct 01 2013

Keywords

• nonn

Examples

			a(1) = 3 because 2 + 3 + 5 = 2*prime(3) and p(3) = 5 is the least such prime summand.
		

Crossrefs

Cf. A013916, A228491.

Programs

Mathematica

z = 2800; f[n_] := Sum[Prime[k], {k, 1, n}]; p[n_] := If[PrimeQ[f[n]/2], 1, 0]; t = Table[p[n], {n, 1, z}]; Flatten[Position[t, 1]]