%I #9 Aug 25 2024 10:00:34
%S 1,1,1,1,4,1,2,2,3,4,10,1,2,2,4,4,4,3,18,4,2,10,11,2,20,2,9,2,14,4,30,
%T 8,10,4,4,3,36,18,2,4,40,2,21,10,12,11,46,4,14,20,4,2,13,9,20,2,18,14,
%U 58,4,3,30,6,16,5,10,66,4,11,4,70,6,72,36,20,18,10,2,39,4,27,40,82,2,4
%N Number of powers of 13 modulo n.
%H Amiram Eldar, <a href="/A054713/b054713.txt">Table of n, a(n) for n = 1..10000</a>
%t a[n_] := Module[{e = IntegerExponent[n, 13]}, e + MultiplicativeOrder[13, n/13^e]]; Array[a, 100] (* _Amiram Eldar_, Aug 25 2024 *)
%Y Cf. A054703 (base 2), A054704 (3), A054705 (4), A054706 (5), A054707 (6), A054708 (7), A054709 (8), A054717 (9), A054710 (10), A351524 (11), A054712 (12), A054714 (14), A054715 (15), A054716 (16).
%K easy,nonn
%O 1,5
%A _Henry Bottomley_, Apr 20 2000