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
Keywords
Examples
511 is composite and the average of the consecutive primes 503, 509 and 521. Thus, 511 is in the sequence.
Links
- Harvey P. Dale, Table of n, a(n) for n = 1..5000
Crossrefs
Cf. A242218 (subsequence of semiprimes).
Programs
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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 *)