A280846 Numbers k such that all four of the numbers 2^k +- 2k +- 1 are nonprime.

9, 10, 16, 17, 19, 20, 21, 22, 23, 24, 26, 29, 30, 33, 34, 36, 37, 38, 39, 40, 42, 43, 44, 45, 46, 47, 48, 49, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 82, 83, 84, 86, 87, 88, 89, 90, 91

Offset

1,1

Links

Table of n, a(n) for n=1..65.

Example

For k=9, 2^k +- 2k +- 1 produces 531, 529, 495, and 493, none of which are prime.

Mathematica

Select[Range[100], NoneTrue[Flatten[{2^#+2#+{1, -1}, 2^#-2#+{1, -1}}], PrimeQ]&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Aug 24 2018 *)

Crossrefs

Cf. A061761 (numbers of the form 2^n + 2*n - 1), A105330 (numbers n such that 2^(n+1) + 2n + 1 is prime), A163115 (primes of the form 2^n + 2*n + 1), A173168 (primes of the form 2^k + 2k - 1). - Jon E. Schoenfield, Jan 22 2017

Sequence in context: A003135 A105742 A105834 * A121061 A106690 A173015

Adjacent sequences: A280843 A280844 A280845 * A280847 A280848 A280849

Keyword

nonn

Author

Maverick K. Morrison, Jan 15 2017

Status

approved