cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A309770 Numbers that are sums of one or more consecutive primes in more than one way.

Original entry on oeis.org

5, 17, 23, 31, 36, 41, 53, 59, 60, 67, 71, 72, 83, 90, 97, 100, 101, 109, 112, 119, 120, 127, 131, 138, 139, 143, 152, 173, 180, 181, 187, 197, 199, 204, 210, 211, 221, 223, 228, 233, 240, 251, 258, 263, 269, 271, 276, 281, 287, 300, 304, 311, 323, 330, 331, 340, 349
Offset: 1

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Author

Ilya Gutkovskiy, Aug 16 2019

Keywords

Comments

Contains A067372 as a subsequence.

Examples

			5 is in the sequence because it can be written as either 5 or 2 + 3.
36 is the sequence because it can be written as either 5 + 7 + 11 + 13 or 17 + 19.
		

Crossrefs

Programs

  • Maple
    N:= 1000: # for terms <= N
    P:= select(isprime, [2, seq(i,i=3..N,2)]):
    S:= [0,op(ListTools:-PartialSums(P))]:
    V:= Vector(N):
    for i from 1 to nops(S) do
      for j from i-1 to 1 by -1 do
        v:= S[i]-S[j];
        if v > N then break fi;
        V[v]:= V[v]+1;
    od od:
    select(t -> V[t]>1, [$1..N]); # Robert Israel, Aug 22 2019

Formula

A054845(a(n)) > 1.