A366269 Hexagonal numbers which are the sum of the first k primes, for some k >= 0.

0, 28, 54047322253, 14756071005948636, 600605016143706003, 41181981873797476176, 240580227206205322973571

Offset

1,2

Links

Table of n, a(n) for n=1..7.

Wikipedia, Hexagonal number.

Index to sequences related to polygonal numbers

Formula

a(n) = A007504(A366270(n)).

Example

28 is a term because it's both a hexagonal number and the sum of the first five primes (2 + 3 + 5 + 7 + 11).

Mathematica

A366269list[kmax_]:=Module[{p=0}, Join[{0}, Table[If[IntegerQ[(Sqrt[8(p+=Prime[k])+1]+1)/4], p, Nothing], {k, kmax}]]]; A366269list[10^5]

Crossrefs

Intersection of A000384 with A007504.

Subsequence of A066527.

Cf. A061890, A364691, A364694, A366270 (corresponding k values).

Sequence in context: A234620 A137942 A099090 * A123269 A067158 A243001

Adjacent sequences: A366266 A366267 A366268 * A366270 A366271 A366272

Keyword

nonn,hard,more

Author

Paolo Xausa, Oct 06 2023

Status

approved