OFFSET
1,2
COMMENTS
MATHEMATICA
f[n_] := 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, Return[1]]; k++; s = s + Prime[n - k] + Prime[n + k]]; 0]; f[1] = 0; Do[ f[n], {n, 10000}]; s = Prime[ Select[ Range[ 10000], f[ # ] == 1 &]]; Table[ Length[ Select[s, # < 10^n &]], {n, 5}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert G. Wilson v, Jul 03 2004
EXTENSIONS
a(6)-a(7) from Donovan Johnson, Apr 09 2010
STATUS
approved