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A182373
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Positive integers k such that k*3^k - 2 is prime.
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1
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3, 5, 7, 37, 45, 53, 179, 277, 721, 2087, 6197, 6317, 8775, 12781, 38943, 47273, 50507
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OFFSET
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1,1
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COMMENTS
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Similar to A060353, and to the Woodall primes, A050918. The next term in the sequence is unknown; if the sequence is infinite, the next term is greater than 5000.
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LINKS
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EXAMPLE
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79 = 3*3^3 - 2; 1213 = 5*3^5 - 2; 15307 = 7*3^7 - 2.
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MAPLE
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#choose N large, then S is the desired set
f:=n->n*3^n - 2:
S:={}:
for n from 0 to N do if(isprime(f(n))) then S:=S union {n}: fi: od
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MATHEMATICA
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Select[Range[2100], PrimeQ[#*3^# - 2] &] (* Jayanta Basu, Jun 01 2013 *)
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PROG
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(PARI) for(n=1, 1e6, if(ispseudoprime(3^n*n - 2), print1(n, ", "))) \\ Altug Alkan, Dec 01 2015
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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