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A135590 Numbers n such that n^2 + 1 is a Sarrus number (pseudoprime to base 2). 3
216, 948, 1560, 4872, 8208, 9828, 18200, 29640, 37024, 65536, 89550, 283800, 535920, 592956, 649800, 825930, 1042320, 1382400, 1536220, 3688230, 4215120, 4321800, 5103210, 19078930, 21415680, 24471720, 214067490, 435457620, 535019100 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Note that A000215(5) corresponds to a(10), and A000215(6) corresponds to a(33), and in general when A000215(n) is composite, this sequence has corresponding entry. - Jeppe Stig Nielsen, Mar 26 2016

LINKS

Jeppe Stig Nielsen, Table of n, a(n) for n = 1..33

MATHEMATICA

fQ[n_] := ( !PrimeQ[n^2 + 1] && PowerMod[2, n^2, n^2 + 1] == 1); lst = {}; Do[ If[ fQ@ n, AppendTo[lst, n]], {n, 2, 440000000, 2}]; lst (* Robert G. Wilson v, Apr 18 2008 *)

PROG

(PARI) is(n) = {Mod(2, n)^(n-1)==1 && !ispseudoprime(n) && n > 1};

for(n=1, 1e10, if(is(n^2+1), print1(n, ", "))); \\ Altug Alkan, Mar 26 2016

CROSSREFS

Cf. A001567.

Sequence in context: A066890 A242296 A223507 * A187859 A250137 A109399

Adjacent sequences:  A135587 A135588 A135589 * A135591 A135592 A135593

KEYWORD

nonn

AUTHOR

Jason Earls, Feb 25 2008

EXTENSIONS

More terms from Robert G. Wilson v, Apr 18 2008

STATUS

approved

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Last modified January 20 18:02 EST 2022. Contains 350472 sequences. (Running on oeis4.)