login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A228490 Numbers k for which prime(1) + ... + prime(k) = 2*prime(m) for some m. 1
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..51.

EXAMPLE

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

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]]

CROSSREFS

Cf.  A013916, A228491.

Sequence in context: A095124 A204254 A144030 * A130294 A321968 A100772

Adjacent sequences:  A228487 A228488 A228489 * A228491 A228492 A228493

KEYWORD

nonn

AUTHOR

Clark Kimberling, Oct 01 2013

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified September 19 21:42 EDT 2020. Contains 337184 sequences. (Running on oeis4.)