

A180247


Prime Brier numbers: prime n such that for all k >= 1 the numbers n*2^k + 1 and n*2^k  1 are composite.


16



10439679896374780276373, 21444598169181578466233, 105404490005793363299729, 178328409866851219182953, 239365215362656954573813, 378418904967987321998467, 422280395899865397194393, 474362792344501650476113, 490393518369132405769309
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OFFSET

1,1


COMMENTS

WARNING: These are just the smallest examples known  there may be smaller ones. Even the first term is uncertain.  N. J. A. Sloane, Jun 20 2017
There are no prime Brier numbers below 10^10.  Arkadiusz Wesolowski, Jan 12 2011
It is a conjecture that every such number has more than 11 digits. In 2011 I have calculated that for any prime n < 10^11 there is a k such that either n*2^k + 1 or n*2^k  1 has all its prime factors greater than 1321.  Arkadiusz Wesolowski, Feb 03 2016
The first term was found by Dan Ismailescu and Peter Seho Park and the next two by Christophe Clavier (see below). See also A076335.  N. J. A. Sloane, Jan 03 2014
a(4)a(9) computed in 2017 by the author.


LINKS

Table of n, a(n) for n=1..9.
D. Baczkowski, J. Eitner, C. E. Finch, B. Suminski, M. Kozek, Polygonal, Sierpinski, and Riesel numbers, Journal of Integer, 2015 Vol 18. #15.8.1.
Chris Caldwell, The Prime Glossary, Riesel number
Chris Caldwell, The Prime Glossary, Sierpinski number
Christophe Clavier, 14 new Brier numbers
Fred Cohen and J. L. Selfridge, Not every number is the sum or difference of two prime powers, Math. Comput. 29 (1975), pp. 7981.
P. Erdős, On integers of the form 2^k + p and some related problems, Summa Brasil. Math. 2 (1950), pp. 113123.
Yves Gallot, A search for some small Brier numbers, 2000.
G. L. Honaker, Jr. and Chris Caldwell, Prime Curios! 6992565235279559197457863
Dan Ismailescu and Peter Seho Park, On Pairwise Intersections of the Fibonacci, Sierpiński, and Riesel Sequences, Journal of Integer Sequences, 16 (2013), #13.9.8.
Joe McLean, Brier Numbers [Cached copy]
Carlos Rivera, Problem 52
Eric Weisstein's World of Mathematics, Brier Number


CROSSREFS

Cf. A194591, A194600, A194603, A194606, A194607, A194608, A194635, A194636, A194637, A194638, A194639, A076336, A076337, A040081, A040076, A103963, A103964, A038699, A050921, A064699, A052333, A003261.
These are the primes in A076335.
Sequence in context: A280301 A115542 A171265 * A095440 A162033 A246254
Adjacent sequences: A180244 A180245 A180246 * A180248 A180249 A180250


KEYWORD

nonn


AUTHOR

Arkadiusz Wesolowski, Aug 19 2010


EXTENSIONS

Entry revised by N. J. A. Sloane, Jan 03 2014
Entry revised by Arkadiusz Wesolowski, May 29 2017


STATUS

approved



