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 A200816 Numbers k such that (2^k - k)*2^k + 1 is prime. 7
 1, 3, 4, 10, 11, 16, 47, 57, 69, 166, 327, 460, 1108, 4740, 20760, 21143, 27779, 34293, 34311 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS The generalization of this sequence is possible with the primes of the form (b^n +- k)*b^n +- 1. LINKS Table of n, a(n) for n=1..19. Henri Lifchitz, New forms of primes EXAMPLE 4 is in the sequence because (2^4 - 4)*2^4 + 1 = 193 is prime. MATHEMATICA lst={}; Do[If[PrimeQ[(2^n - n)*2^n+1], AppendTo[lst, n]], {n, 10^3}]; lst PROG (PARI) is(n)=ispseudoprime((2^n-n)<

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Last modified August 3 12:22 EDT 2024. Contains 374893 sequences. (Running on oeis4.)