The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A266694 Numbers n such that 2*n*3^n + 1 is prime. 1
 1, 2, 3, 14, 19, 21, 27, 33, 46, 70, 80, 441, 540, 567, 625, 1057, 1119, 1213, 1542, 4263, 4419, 4507, 5186, 7345, 8626, 8853, 11256, 12885, 14688, 15236, 17697, 26770, 57801, 71665 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Primes: 2, 3, 19, 1213, 4507, ... No further terms < 10^5. - Ray Chandler, Apr 13 2016 LINKS Table of n, a(n) for n=1..34. EXAMPLE 1 is in this sequence because 2*1*3^1 + 1 = 7 is prime. MATHEMATICA Select[Range[1600], PrimeQ[2 # 3^# + 1] &] (* Vincenzo Librandi, Jan 03 2016 *) PROG (Magma) [n: n in [1..2000]| IsPrime(2*n*3^n+1)]; // Vincenzo Librandi, Jan 03 2016 (PARI) is(n)=ispseudoprime(2*n*3^n+1) \\ Charles R Greathouse IV, Feb 08 2016 CROSSREFS Cf. A006552. Sequence in context: A041733 A212112 A107083 * A284928 A374232 A294405 Adjacent sequences: A266691 A266692 A266693 * A266695 A266696 A266697 KEYWORD nonn,more AUTHOR Juri-Stepan Gerasimov, Jan 02 2016 EXTENSIONS a(24) and a(26) inserted by Charles R Greathouse IV, Feb 08 2016 a(28)-a(30) from Charles R Greathouse IV, Feb 08 2016 a(31)-a(32) from Ray Chandler, Apr 05 2016 a(33) from Ray Chandler, Apr 08 2016 a(34) from Ray Chandler, Apr 09 2016 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified September 12 11:37 EDT 2024. Contains 375851 sequences. (Running on oeis4.)