

A228357


Numbers n such that sum of all primes <=n is not prime.


1



1, 5, 6, 11, 12, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 41, 42, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85
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OFFSET

1,2


LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000


EXAMPLE

6 is in the sequence since 2+3+5=10 is not prime.


MATHEMATICA

t = {}; s = 0; Do[If [PrimeQ[n], s+ = n]; If[!PrimeQ[s], AppendTo[t, n]], {n, 120}]; t
Position[Accumulate[Table[If[PrimeQ[n], n, 0], {n, 100}]], _?(!PrimeQ[ #]&)]// Flatten//Rest (* Harvey P. Dale, Jul 02 2018 *)


PROG

(MAGMA) [n: n in [1..120]  not IsPrime(s) where s is &+PrimesUpTo(n)];


CROSSREFS

Cf. A034387, A228102.
Sequence in context: A139071 A092296 A046608 * A215033 A047264 A277095
Adjacent sequences: A228354 A228355 A228356 * A228358 A228359 A228360


KEYWORD

nonn,easy


AUTHOR

Vincenzo Librandi, Aug 21 2013


STATUS

approved



