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A350084 a(n) = ord(2,A006935(n)/2), where ord(k,m) is the multiplicative order of k modulo m. 2

%I #14 Jul 21 2024 03:47:10

%S 1,261,165,275,13425,1485,1305,32085,825,3465,2093,3135,495,495,261,

%T 847,9405,552189,198561,261,579261,2475,6237,166725,111111,3393,3565,

%U 25245,18585,4437,891891,309455,37125,4833,2301585,14355,11781,3315,915,84975,35259

%N a(n) = ord(2,A006935(n)/2), where ord(k,m) is the multiplicative order of k modulo m.

%C List of ord(2,k) where k ranges over the odd numbers such that 2^(2*k-1) == 1 (mod k).

%H Amiram Eldar, <a href="/A350084/b350084.txt">Table of n, a(n) for n = 1..1319</a>

%F a(n) = ord(2,A347906(n)) = (A006935(n) - 1) / A350083(n).

%e A006935(2) = 161038, so a(2) = ord(2,161038/2) = 261.

%e A006935(3) = 215326, so a(3) = ord(2,215326/2) = 165.

%o (PARI) list(lim) = my(v=[],d); forstep(k=1, lim, 2, if((2*k-1)%(d=znorder(Mod(2,k)))==0, v=concat(v,d))); v \\ gives a(n) for A347906(n) <= lim

%Y Cf. A006935, A347906, A350083, A306413, A306414.

%K nonn

%O 1,2

%A _Jianing Song_, Dec 12 2021

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Last modified August 13 18:29 EDT 2024. Contains 375144 sequences. (Running on oeis4.)