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A366270
Nonnegative integers k such that the sum of the first k primes is a hexagonal number.
4
0, 5, 93448, 39545957, 240439822, 1894541497, 132563927578
OFFSET
1,2
EXAMPLE
5 is a term because the sum of the first five primes (2 + 3 + 5 + 7 + 11 = 28) is a hexagonal number.
MATHEMATICA
A366270list[kmax_]:=Module[{p=0}, Join[{0}, Table[If[IntegerQ[(Sqrt[8(p+=Prime[k])+1]+1)/4], k, Nothing], {k, kmax}]]]; A366270list[10^5]
CROSSREFS
Subsequence of A175133.
Cf. A000384, A007504, A033997, A364695, A364696, A366269 (corresponding hexagonal numbers).
Sequence in context: A263174 A123591 A133381 * A236066 A151589 A243114
KEYWORD
nonn,hard,more
AUTHOR
Paolo Xausa, Oct 06 2023
STATUS
approved