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Number of powers of 7 modulo n.
15

%I #13 Aug 25 2024 10:00:18

%S 1,1,1,2,4,1,2,2,3,4,10,2,12,2,4,2,16,3,3,4,2,10,22,2,4,12,9,3,7,4,15,

%T 4,10,16,5,6,9,3,12,4,40,2,6,10,12,22,23,2,3,4,16,12,26,9,20,3,3,7,29,

%U 4,60,15,4,8,12,10,66,16,22,5,70,6,24,9,4,6,11,12,78,4,27,40,41,3,16,6

%N Number of powers of 7 modulo n.

%H Amiram Eldar, <a href="/A054708/b054708.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..1000 from David W. Wilson)

%F a(n) = A007738(n) + A214411(n). - _Amiram Eldar_, Aug 25 2024

%t a[n_] := Module[{e = IntegerExponent[n, 7]}, e + MultiplicativeOrder[7, n/7^e]]; Array[a, 100] (* _Amiram Eldar_, Aug 25 2024 *)

%Y Cf. A007738, A214411.

%Y Cf. A054703 (base 2), A054704 (3), A054705 (4), A054706 (5), A054707 (6), A054709 (8), A054717 (9), A054710 (10), A351524 (11), A054712 (12), A054713 (13), A054714 (14), A054715 (15), A054716 (16).

%K easy,nonn

%O 1,4

%A _Henry Bottomley_, Apr 20 2000