A345363 Composite numbers that are the exact average of three consecutive primes.

511, 537, 999, 1073, 1239, 1461, 1501, 1541, 1763, 1773, 1899, 1917, 2071, 2181, 2401, 2409, 2449, 3059, 3069, 3179, 3201, 3509, 3807, 4081, 4101, 4179, 4387, 4399, 4437, 4467, 4559, 4607, 4681, 4705, 4879, 5089, 5211, 5257, 5271, 5373, 5429, 5757, 5829, 6415, 6621, 6671

Offset

1,1

Links

Harvey P. Dale, Table of n, a(n) for n = 1..5000

Example

511 is composite and the average of the consecutive primes 503, 509 and 521. Thus, 511 is in the sequence.

Mathematica

Select[Table[(Prime[n] + Prime[n + 1] + Prime[n + 2])/3, {n, 2000}], IntegerQ[#] && ! PrimeQ[#] &]
Select[Mean/@Partition[Prime[Range[1000]], 3, 1], IntegerQ[#]&&CompositeQ[#]&] (* Harvey P. Dale, Feb 01 2025 *)

Crossrefs

Cf. A242218 (subsequence of semiprimes).

Sequence in context: A196289 A027494 A145588 * A242218 A051985 A103206

Adjacent sequences: A345360 A345361 A345362 * A345364 A345365 A345366

Keyword

nonn

Author

Tanya Khovanova, Jun 16 2021

Status

approved