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A250396
a(n) is the smallest prime greater than 2^n such that 2 is a primitive root modulo a(n).
2
3, 3, 5, 11, 19, 37, 67, 131, 269, 523, 1061, 2053, 4099, 8219, 16421, 32771, 65539, 131213, 262147, 524309, 1048589, 2097211, 4194371, 8388619, 16777259, 33554467, 67108933, 134217773, 268435459, 536871019, 1073741827, 2147483659, 4294967357, 8589934621, 17179869269, 34359738421, 68719476851, 137438953741
OFFSET
0,1
REFERENCES
Henri Cohen, A Course in Computational Algebraic Number Theory, Springer Verlag, (1993)
LINKS
MATHEMATICA
With[{n = 20},
Module[{p = NextPrime[2^n]},
While[FreeQ[PrimitiveRootList[p], 2], p = NextPrime[p]]; p]]
PROG
(PARI) a(n)=forprime(p=2^n+1, , if(znorder(Mod(2, p))==p-1, return(p))); \\ Joerg Arndt, Nov 21 2014
CROSSREFS
Cf. A104080 (smallest prime >= 2^n).
Sequence in context: A084656 A073749 A299590 * A201866 A191632 A146918
KEYWORD
nonn
AUTHOR
Morgan L. Owens, Nov 21 2014
STATUS
approved