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 A134303 Least k such that k*2^n*(k*2^n-1)-1 is prime. 3
 2, 1, 2, 1, 1, 3, 4, 2, 1, 1, 19, 15, 13, 9, 8, 4, 2, 1, 35, 29, 31, 26, 13, 12, 6, 3, 27, 25, 31, 20, 10, 5, 32, 16, 8, 4, 2, 1, 17, 9, 16, 8, 4, 2, 1, 5, 8, 4, 2, 1, 64, 32, 16, 8, 4, 2, 1, 29, 120, 60, 30, 15, 35, 41, 37, 60, 30, 15 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Pierre CAMI, Table of n, a(n) for n = 1..2500 MAPLE A134303 := proc(n)     for k from 1 do         k*2^n*(k*2^n-1)-1 ;         if isprime(%) then             return k;         end if;     end do: end proc: seq(A134303(n), n=1..80) ; # R. J. Mathar, Nov 30 2011 MATHEMATICA lk[n_]:=Module[{k=1, n2=2^n}, While[!PrimeQ[k*n2(k n2-1)-1], k++]; k]; Array[ lk, 70] (* Harvey P. Dale, Sep 29 2017 *) CROSSREFS Cf. A134304, A134305. Sequence in context: A205810 A139368 A266506 * A078997 A024680 A083531 Adjacent sequences:  A134300 A134301 A134302 * A134304 A134305 A134306 KEYWORD nonn AUTHOR Pierre CAMI, Oct 19 2007 STATUS approved

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Last modified June 18 12:13 EDT 2021. Contains 345098 sequences. (Running on oeis4.)