This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A054715 #9 Aug 25 2024 10:00:42
%S A054715 1,1,2,2,2,2,1,2,3,2,5,3,12,1,2,2,8,3,18,3,2,5,22,3,3,12,4,2,28,2,10,
%T A054715 2,6,8,2,4,36,18,13,3,40,2,21,10,3,22,46,3,7,3,9,12,13,4,6,2,19,28,29,
%U A054715 3,15,10,3,4,13,6,11,8,23,2,35,4,72,36,3,18,5,13,26,3,5,40,82,3,9,21,29
%N A054715 Number of powers of 15 modulo n.
%H A054715 Amiram Eldar, <a href="/A054715/b054715.txt">Table of n, a(n) for n = 1..10000</a>
%t A054715 a[n_] := Module[{e = IntegerExponent[n, {3, 5}]}, Max[e] + MultiplicativeOrder[15, n/Times @@ ({3, 5}^e)]]; Array[a, 100] (* _Amiram Eldar_, Aug 25 2024 *)
%Y A054715 Cf. A054703 (base 2), A054704 (3), A054705 (4), A054706 (5), A054707 (6), A054708 (7), A054709 (8), A054717 (9), A054710 (10), A351524 (11), A054712 (12), A054713 (13), A054714 (14), A054716 (16).
%K A054715 easy,nonn
%O A054715 1,3
%A A054715 _Henry Bottomley_, Apr 20 2000