login
A171161
Sophie Germain primes p surrounded by Sophie Germain primes.
0
2, 3, 20759, 103619, 145109, 148853, 199109, 291503, 353459, 356591, 362759, 367733, 475523, 521831, 527123, 552059, 603191, 609809, 639839, 691979, 726419, 810809, 812939, 825491, 940421, 980471, 998213, 1103561, 1117793, 1132811
OFFSET
1,1
MATHEMATICA
PrimeNext[n_]:=Module[{k}, k=n+1; While[ !PrimeQ[k], k++ ]; k]; PrimePrev[n_]:=Module[{k}, k=n-1; While[ !PrimeQ[k], k-- ]; k]; f[n_]:=PrimeQ[2*n+1]; lst={}; Do[p=Prime[n]; If[f[p], If[f[PrimePrev[p]]&&f[PrimeNext[p]], AppendTo[lst, p]]], {n, 9!}]; lst
CROSSREFS
Sequence in context: A115640 A212494 A197635 * A101445 A128668 A216977
KEYWORD
nonn
AUTHOR
STATUS
approved