A081727 - OEIS

%I #17 Sep 20 2020 01:22:41

%S 1,1,2,1,2,2,6,4,6,2,10,2,6,6,2,8,8,6,18,2,6,10,22,4,10,6,18,6,14,2,

%T 30,16,10,8,6,6,18,18,6,4,20,6,42,10,6,22,46,8,42,10,8,6,26,18,10,12,

%U 18,14,58,2,30,30,6,32,6,10,66,8,22,6,70,12,36,18,10

%N Length of periods of Euler numbers modulo n.

%C Terms after a(126) need more Euler numbers to check the period length. There are 85 unknown terms starting from a(127) till a(500) when 242 Euler numbers are used. - _Hakan Icoz_, Sep 06 2020

%H Hakan Icoz, <a href="/A081727/b081727.txt">Table of n, a(n) for n = 1..125</a>

%F a(n) = n-1 if n=2, 3, 7, 11, 19, 23, 31...is a prime == 2 or 3 (mod 4) (A045326).

%e A000364 modulo 5 gives : 1,1,0,1,0,1,0,1,0,1,0,... with period (1,0) of length 2, hence a(5)=2.

%Y Cf. A000364, A045326.

%K nonn

%O 1,3

%A _Benoit Cloitre_, Apr 06 2003

%E More terms from _Hakan Icoz_, Sep 06 2020