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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 (list; graph; refs; listen; history; text; internal format)
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. 79-81.

P. Erdős, On integers of the form 2^k + p and some related problems, Summa Brasil. Math. 2 (1950), pp. 113-123.

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

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Last modified August 19 08:57 EDT 2017. Contains 290794 sequences.