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 A109387 Numbers k such that 3^k - k^3 is prime. 11
 1, 4, 10, 52, 112, 212, 346, 406, 512, 13904, 76610, 89746, 114892 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Terms <= 512 correspond to certified primes. Next term after 13904 is greater than 20000. LINKS Table of n, a(n) for n=1..13. EXAMPLE 4 is a term because 3^4 - 4^3 = 17 is prime. 3^10 - 10^3 = 58049 is prime, hence 10 is a term. MATHEMATICA Do[If[PrimeQ[3^n - n^3], Print[n]], {n, 1, 20000}] PROG (PARI) is(n)=isprime(3^n-n^3) \\ Charles R Greathouse IV, Feb 17 2017 CROSSREFS Sequence in context: A351046 A208236 A032495 * A362819 A018844 A007027 Adjacent sequences: A109384 A109385 A109386 * A109388 A109389 A109390 KEYWORD hard,more,nonn AUTHOR Ryan Propper, Jun 26 2005 EXTENSIONS Two more terms from Donovan Johnson, Feb 26 2008 a(13) from Norbert Schneider submitted by Robert Price, Mar 16 2019 STATUS approved

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Last modified June 2 20:13 EDT 2023. Contains 363100 sequences. (Running on oeis4.)