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

 

Logo

Invitation: celebrating 50 years of OEIS, 250000 sequences, and Sloane's 75th, there will be a conference at DIMACS, Rutgers, Oct 9-10 2014.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A129802 Possible bases for Pepin's primality test for Fermat numbers. 0
3, 5, 6, 7, 10, 12, 14, 20, 24, 27, 28, 39, 40, 41, 45, 48, 51, 54, 56, 63, 65, 75, 78, 80, 82, 85, 90, 91, 96, 102, 105, 108, 112, 119, 125, 126, 130, 147, 150, 156, 160, 164, 170, 175, 180, 182, 192, 204, 210, 216, 224, 238, 243, 245, 250, 252, 260, 291, 294, 300 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Prime elements of this sequence are given by A102742.

LINKS

Table of n, a(n) for n=1..60.

Eric Weisstein's World of Mathematics, Pepin's Test

FORMULA

A positive integer 2^k*m, where m is odd and k>=0, belongs to this sequence iff the Jacobi symbol (F_n/m)=1 only for a finite number of Fermat numbers F_n=A000215(n).

PROG

(PARI) { isPepin(n) = local(s, S=Set(), t); n\=2^valuation(n, 2); s=Mod(3, n); while( !setsearch(S, s), S=setunion(S, [s]); s=(s-1)^2+1); t=s; until( t==s, if( kronecker(lift(t), n)==1, return(0)); t=(t-1)^2+1); 1 } for(n=2, 1000, if(isPepin(n), print1(n, ", ")))

CROSSREFS

Cf. A000215, A019434, A060377, A102742.

Sequence in context: A028811 A034035 A136804 * A023854 A092559 A242076

Adjacent sequences:  A129799 A129800 A129801 * A129803 A129804 A129805

KEYWORD

nonn

AUTHOR

Max Alekseyev, Jun 14 2007, corrected Dec 29 2007. Thanks to Ant King for pointing out an error in the earlier version of this sequence.

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement .

Last modified October 2 05:40 EDT 2014. Contains 247537 sequences.