A126204 Least prime representable as the arithmetic mean of two other primes in n different ways.

2, 5, 11, 17, 37, 53, 89, 71, 101, 179, 137, 193, 233, 257, 251, 401, 311, 373, 347, 457, 661, 479, 547, 599, 617, 641, 683, 907, 881, 773, 827, 809, 941, 1033, 977, 1289, 1201, 1187, 1229, 1223, 1277, 1361, 1597, 1493, 1447, 1499, 1451, 1549, 1487, 1709, 1933

Offset

0,1

Comments

a(n)=A000040(A137700(n)); A071681(A137700(n))=n and A071681(m)<>n for m < A137700(n). - Reinhard Zumkeller, Feb 07 2008

Links

Robert G. Wilson v, Table of n, a(n) for n = 0..11300

Mathematica

f[n_] := Block[{c = 0, k = PrimePi@n - 1}, While[k > 0, If[ PrimeQ[2n - Prime@k], c++ ]; k-- ]; c]; t = Table[0, {1000}]; Do[ p = Prime@n; a = f@p; If[a < 1001 && t[[a]] == 0, t[[a]] = p; Print[{a, p}]], {n, 8900}]

Crossrefs

Cf. A071681.

Sequence in context: A059987 A027426 A133928 * A091936 A153145 A174003

Adjacent sequences: A126201 A126202 A126203 * A126205 A126206 A126207

Keyword

nonn

Author

Robert G. Wilson v, Mar 22 2007

Extensions

Start of b-file modified to match sequence by N. J. A. Sloane, Aug 31 2009

Status

approved