%I #9 Aug 01 2015 14:08:15
%S 6,10,30,66,946,3310,10470,36370,60126,104106,128766,170710,323670,
%T 369370,398266,596926,813430,1145166,1494690,2384866,5960746,6376126,
%U 8178346,18327310,31380922,34102630,37105762,40796526,41950966,41983446
%N Even pseudoprimes to base 31.
%H Robert G. Wilson v, <a href="/A130440/b130440.txt">Table of n, a(n) for n = 1..87</a>.
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/FermatPseudoprime.html">Fermat Pseudoprime</a>.
%H <a href="/index/Ps#pseudoprimes">Index entries for sequences related to pseudoprimes</a>
%t Do[ f=PowerMod[ 31, 2n-1, 2n ]; If[ f==1, Print[ 2n ] ], {n,2,500000} ]
%t lst = {}; Do[ If[ PowerMod[31, 2n - 1, 2n] == 1, AppendTo[lst, 2n]], {n, 2, 2^31}]; lst (* _Robert G. Wilson v_, Jun 01 2007 *)
%Y Cf. A020159, A006935, A130433, A090082, A090083, A090084, A090085, A130434, A130435, A130436, A130437, A130438, A130439, A130441, A130442, A130443.
%K nonn
%O 1,1
%A _Alexander Adamchuk_, May 26 2007
%E More terms from _Robert G. Wilson v_, Jun 01 2007
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