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A240942
Numbers k that divide 2^k + 9.
4
1, 11, 121, 323, 117283, 432091, 4132384531, 15516834659, 15941429747, 98953554491, 3272831195051, 7362974489179, 26306805687881, 33869035218491, 280980898827691
OFFSET
1,2
COMMENTS
No other terms below 10^15. Some larger terms: 53496121130110340001650284048539458491, 136243118444105327963550175410279542214992801356720577. - Max Alekseyev, Sep 29 2016
EXAMPLE
2^11 + 9 = 2057 is divisible by 11. Thus 11 is a term of this sequence.
MAPLE
select(n -> 9 + 2 &^ n mod n = 0, [$1..10^6]); # Robert Israel, Aug 04 2014
PROG
(PARI) for(n=1, 10^9, if(Mod(2, n)^n==-9, print1(n, ", "); ); );
CROSSREFS
KEYWORD
nonn,more,hard
AUTHOR
Derek Orr, Aug 04 2014
EXTENSIONS
a(7)-a(10) from Lars Blomberg, Nov 05 2014
a(11)-a(15) from Max Alekseyev, Sep 29 2016
STATUS
approved