A090084 Even pseudoprimes to base 11.

10, 70, 190, 1330, 8170, 9730, 24130, 28462, 58030, 98458, 143830, 144886, 327370, 856786, 1580230, 1620130, 3536470, 5274970, 6082490, 6376126, 6792710, 8066170, 8610610, 14076910, 17728930, 27275158, 42447406, 52970386, 53497978, 68925130

Offset: 1

Author

Labos Elemer, Nov 25 2003

Keywords

• nonn

Links

• Amiram Eldar, Table of n, a(n) for n = 1..165 (terms below 10^11; terms 1..84 from Robert G. Wilson v)
• Eric Weisstein's World of Mathematics, Fermat Pseudoprime.
• Index entries for sequences related to pseudoprimes.

Crossrefs

Cf. A020139.

Cf. A006935, A130433, A090082, A090083, A090085, A130434, A130435, A130436, A130438, A130439, A130440, A130441, A130442, A130443.

Programs

Mathematica

Do[ f=PowerMod[ 11, 2n-1, 2n ]; If[ f==1, Print[ 2n ] ],{n,2,800000} ] (* Alexander Adamchuk, May 26 2007 *)
lst = {}; Do[ If[ PowerMod[11, 2n - 1, 2n] == 1, AppendTo[lst, 2n]], {n, 2, 2*10^9}]; lst (* Robert G. Wilson v, Jun 01 2007 *)
Select[Range[4,68926000,2],PowerMod[11,#-1,#]==1&] (* Harvey P. Dale, Oct 16 2021 *)

PARI

is(k) = k > 2 && !(k % 2) &&  Mod(11, k)^(k-1) == 1; \\ Amiram Eldar, Sep 18 2024

Extensions

More terms from Alexander Adamchuk, May 26 2007

Further terms from Robert G. Wilson v, Jun 01 2007