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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A259178 Numbers k such that (4^k - 1)/3 is squarefree. 2
 1, 2, 3, 4, 5, 6, 7, 8, 11, 12, 13, 14, 15, 16, 17, 19, 22, 23, 24, 25, 26, 28, 29, 31, 32, 33, 34, 35, 37, 38, 39, 41, 43, 44, 46, 47, 48, 49, 51, 52, 53, 56, 57, 58, 59, 61, 62, 64, 65, 66, 67, 69, 71, 73, 74, 75, 76, 77, 79, 82, 83, 85, 86, 87, 88, 89, 91, 92, 93, 94, 95, 96, 97, 98, 101, 102, 103, 104, 106, 107, 109, 111 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Amiram Eldar, Table of n, a(n) for n = 1..467 MATHEMATICA Select[Range[0, 120], SquareFreeQ[((4^# - 1) / 3)] &] (* Vincenzo Librandi, Aug 03 2015 *) PROG (MAGMA) [n: n in [1..115] | IsSquarefree((4^n-1) div 3)]; // Vincenzo Librandi, Aug 03 2015 (PARI) isok(k) = issquarefree((4^k-1)/3); \\ Michel Marcus, Feb 25 2021 CROSSREFS Complement of A260042. Cf. A002450, A005117, A008966. Sequence in context: A039272 A039209 A214678 * A032880 A032847 A023778 Adjacent sequences:  A259175 A259176 A259177 * A259179 A259180 A259181 KEYWORD nonn AUTHOR Omar E. Pol, Aug 02 2015 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 May 26 21:56 EDT 2022. Contains 354092 sequences. (Running on oeis4.)