OFFSET
1,1
EXAMPLE
353 is a member because 353 = (281 + ...353 + ... + 421)/23
= (271 + .. + 353 + ... + 433)/27 = (241 + ... + 353 + ... + 461)/37 = (227 + ... + 353 + ... + 487)/45.
MATHEMATICA
f[n_] := Block[{c = 0, k = 1, p = Prime[n], s = Plus @@ Table[ Prime[i], {i, n - 1, n + 1}]}, While[k != n - 1, If[s == (2k + 1)p, c++ ]; k++; s = s + Prime[n - k] + Prime[n + k]]; c]; Prime[ Select[ Range[2, 25797], f[ # ] == 4 &]]
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert G. Wilson v, Jun 28 2004
EXTENSIONS
a(17)-a(31) from Donovan Johnson, Apr 09 2010
STATUS
approved