A163184 - OEIS

%I #8 Mar 27 2017 21:34:35

%S 281,617,1033,1049,1097,1193,1481,1553,1753,1777,2281,2393,2473,2657,

%T 2833,2857,3049,3529,3673,3833,4049,4153,4217,4273,4457,4937,5113,

%U 5297,5881,6121,6449,6481,6521,6529,6569,6761,6793,6841,7121,7129,7481,7577,7817,8081,8233,8537,9001,9137,9209,9241

%N Primes of the form 8k + 1 dividing 2^j + 1 for some odd j.

%C Each term p has the form 2^r*j + 1, where r >= 3, j is odd, and ord_p(-2) divides j.

%e 281 is in the sequence as 281 = 2^3*35 + 1 and 281 | 2^35 + 1.

%p with(numtheory):A:=NULL:p:=2: for c to 500 do p:=nextprime(p);if order(-2,p) mod 2=1 and p mod 8 = 1 then A:=A,p;;fi;od:A;

%Y Set difference of A163183 and A007520.

%Y Subsequence of A033203, A051071, A051073, A051077, A051085, A051101.

%K easy,nonn

%O 1,1

%A _Christopher J. Smyth_, Jul 22 2009

%E More terms from _Max Alekseyev_, Sep 29 2016