

A182373


Positive integers n such that n*3^n  2 is prime.


1



3, 5, 7, 37, 45, 53, 179, 277, 721, 2087, 6197, 6317, 8775, 12781
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OFFSET

1,1


COMMENTS

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.


LINKS

Table of n, a(n) for n=1..14.


EXAMPLE

79 = 3*3^3  2; 1213 = 5*3^5  2; 15307 = 7*3^7  2.


MAPLE

#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


MATHEMATICA

Select[Range[2100], PrimeQ[#*3^#  2] &] (* Jayanta Basu, Jun 01 2013 *)


PROG

PARI) for(n=1, 1e6, if(ispseudoprime(3^n*n  2), print1(n, ", "))) \\ Altug Alkan, Dec 01 2015


CROSSREFS

Cf. A050918, A060353.
Sequence in context: A154544 A155034 A126359 * A087363 A234569 A037287
Adjacent sequences: A182370 A182371 A182372 * A182374 A182375 A182376


KEYWORD

nonn,more


AUTHOR

Patrick Devlin, Apr 26 2012


EXTENSIONS

a(11)a(14) from Altug Alkan, Dec 01 2015


STATUS

approved



