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A142247
Primes of the form 2^p - 1, 2^p + 1, 2^p - 3, or 2^p + 3, where p is prime.
0
3, 5, 7, 11, 29, 31, 127, 131, 8191, 131071, 524287, 536870909, 2147483647, 2305843009213693951, 147573952589676412931, 618970019642690137449562111, 162259276829213363391578010288127
OFFSET
1,1
FORMULA
Union of A000668, A172041, and A057737. - Jason Yuen, Oct 01 2024
MATHEMATICA
f[n_] := If[PrimeQ[2^Prime[n] - 1] || PrimeQ[2^Prime[n] + 1] || PrimeQ[2^Prime[n] - 3] || PrimeQ[2^Prime[n] + 3], {2^Prime[n] - 1, 2^Prime[n] + 1, 2^Prime[n] - 3, 2^Prime[n] + 3}, {}]; a = Flatten[Table[f[n], {n, 1, 100}]]; Union[Flatten[Table[If[PrimeQ[a[[n]]], a[[n]], {}], {n, 1, Length[a]}]]]
CROSSREFS
KEYWORD
nonn,uned
AUTHOR
Roger L. Bagula, Sep 18 2008
STATUS
approved