|
|
A175521
|
|
Nonprimes n such that 9*n divides 2^(n-1) - 1.
|
|
1
|
|
|
1, 1105, 1387, 1729, 2047, 2701, 2821, 3277, 4033, 4369, 4681, 5461, 6601, 7957, 8911, 10261, 10585, 11305, 13741, 13747, 13981, 14491, 15709, 15841, 16705, 18721, 19951, 23377, 29341, 30121, 30889, 31417, 31609, 31621, 34945, 39865, 41041, 41665, 42799, 46657, 49141, 49981
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
COMMENTS
|
Original name was: Nonprimes n of the form 6m+1 such that (2^(n-1) mod n)=(4^(n-1) mod n)=(8^(n-1) mod n)=..=(k^(n-1) mod n) for k=2,4,8,..,smallest power of 2>n.
|
|
LINKS
|
|
|
EXAMPLE
|
a(1)=1 because 1=6*0+1 and (2^(1-1) mod 1)=(4^(1-1) mod 1)=0.
|
|
MATHEMATICA
|
n = 1; t = {}; While[Length[t] < 100, While[PrimeQ[n] || PowerMod[2, n-1, 9*n] != 1, n = n + 2]; AppendTo[t, n]; n = n + 2]; t (* T. D. Noe, Jul 25 2011 *)
|
|
PROG
|
(PARI) p=0; forprime(q=2, 1e5, for(n=p+1, q-1, if(Mod(2, 9*n)^(n-1)==1, print1(n", "))); p=q) \\ Charles R Greathouse IV, Jul 24 2011
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|