%I A081727
%S A081727 1,1,2,1,2,2,6,4,6,2,10,2,6,6,2,8,8,6,18,2,6,10,22,4,10,6,18,6,14,2,30,
%T A081727 16,10,8,6,6,18,18,6,4
%N A081727 Length of periods of Euler numbers modulo n.
%F A081727 a(n)=n-1 if n=2, 3, 7, 11, 19, 23, 31...is a prime == 2 or 3 (mod 4) 
               (A045326)
%e A081727 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 A081727 Cf. A000364, A045326.
%Y A081727 Sequence in context: A093659 A067541 A054706 this_sequence A000020 A077014 
               A093655
%Y A081727 Adjacent sequences: A081724 A081725 A081726 this_sequence A081728 A081729 
               A081730
%K A081727 more,nonn
%O A081727 1,3
%A A081727 Benoit Cloitre (benoit7848c(AT)orange.fr), Apr 06 2003