login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A087759 Primes n such that 7^n-6^n is composite. 0
5, 11, 13, 17, 19, 23, 31, 37, 43, 47, 53, 59, 61, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283, 293 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,1

LINKS

Table of n, a(n) for n=2..57.

MATHEMATICA

Select[Prime[Range[70]], CompositeQ[7^#-6^#]&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Mar 12 2019 *)

PROG

(PARI) apmb(a, b, n) = { forprime(x=2, n, y=a^x-b^x; if(!ispseudoprime(y), print1(x", "); ) ) }

CROSSREFS

Sequence in context: A082554 A141246 A288445 * A234644 A299791 A230359

Adjacent sequences:  A087756 A087757 A087758 * A087760 A087761 A087762

KEYWORD

nonn

AUTHOR

Cino Hilliard, Oct 26 2003

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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 23 11:05 EDT 2019. Contains 323513 sequences. (Running on oeis4.)