%I A122785
%S A122785 1,4,8,9,14,21,28,341,481,511,561,585,645,651,861,949,1001,1016,1105,
%T A122785 1106,1281,1288,1365,1387,1417,1541,1649,1661,1729,1736,1785,1905,2044,
%U A122785 2047,2169,2465,2501,2696,2701,2821,3145,3171,3201,3277,3605,3641,4005
%N A122785 Nonprimes n such that 8^n==8 (mod n).
%C A122785 Theorem: If both numbers q and 2q-1 are primes and n=q*(2q-1) then 8^n==8 
               (mod n) (n is in the sequence) iff q is of the form 4k+1. 2701,18721,
               49141,104653,226801,665281,721801,... are such terms.
%t A122785 Select[Range[6000], ! PrimeQ[ # ] && Mod[8^#, # ] == Mod[8, # ] &]
%Y A122785 Cf. A020137, A001567.
%Y A122785 Sequence in context: A121763 A110087 A085711 this_sequence A137055 A036349 
               A078177
%Y A122785 Adjacent sequences: A122782 A122783 A122784 this_sequence A122786 A122787 
               A122788
%K A122785 nonn
%O A122785 1,2
%A A122785 Farideh Firoozbakht (mymontain(AT)yahoo.com), Sep 12 2006