This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A156555 Primes of the form 3^k - 4. 1
 5, 23, 239, 10460353199, 617673396283943, 450283905890997359, 36472996377170786399, 19383245667680019896796719, 67585198634817523235520443624317919, 1546132562196033993109383389296863818106322565999 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The next term, a(11), has 84 digits. - Harvey P. Dale, Jul 24 2011 LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..17 F. Firoozbakht, M. F. Hasler, Variations on Euclid's formula for Perfect Numbers, JIS 13 (2010) #10.3.1 Henri & Renaud Lifchitz, PRP Records OpenPFGW Project, Primality Tester FORMULA a(k) = 3^A058959(k) - 4. - M. F. Hasler, Oct 31 2009 EXAMPLE a(1) = 3^2 - 4 = 5 is the smallest prime of that form. - M. F. Hasler, Oct 31 2009 MATHEMATICA Select[3^Range[200]-4, PrimeQ] (* Harvey P. Dale, Jul 24 2011 *) PROG (PARI) for( k=2, 999, is/*pseudo*/prime( p=3^k-4 ) & print1(p", ")) \\ M. F. Hasler, Oct 31 2009 CROSSREFS Cf. A058959. Sequence in context: A322238 A295080 A323993 * A116652 A197936 A198029 Adjacent sequences:  A156552 A156553 A156554 * A156556 A156557 A156558 KEYWORD nonn AUTHOR Vincenzo Librandi, Feb 10 2009 EXTENSIONS a(5) corrected by M. F. Hasler, Oct 31 2009 a(10) from Harvey P. Dale, Jul 24 2011 STATUS approved

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

Last modified March 20 09:35 EDT 2019. Contains 321345 sequences. (Running on oeis4.)