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 A024641 #14 Jul 31 2025 03:51:27 %S A024641 0,1,2,3,4,5,6,40,41,42,43,44,45,46,410,411,412,413,414,415,416,450, %T A024641 451,452,453,454,455,456,4120,4121,4122,4123,4124,4125,4126,4160,4161, %U A024641 4162,4163,4164,4165,4166,4530,4531,4532,4533,4534,4535,4536,41200,41201 %N A024641 n written in fractional base 7/4. %C A024641 To represent a number in base b, if a digit exceeds b-1, subtract b and carry 1. In fractional base a/b, subtract a and carry b. %H A024641 Amiram Eldar, <a href="/A024641/b024641.txt">Table of n, a(n) for n = 0..10000</a> %H A024641 <a href="/index/Ba#base_fractional">Index entries for sequences related to fractional bases</a>. %t A024641 a[n_] := a[n] = If[n == 0, 0, 10 * a[4 * Floor[n/7]] + Mod[n, 7]]; Array[a, 50, 0] (* _Amiram Eldar_, Jul 31 2025 *) %o A024641 (PARI) a(n) = if(n == 0, 0, 10 * a(n\7 * 4) + n % 7); \\ _Amiram Eldar_, Jul 31 2025 %Y A024641 Cf. A245349. %K A024641 nonn,base,easy %O A024641 0,3 %A A024641 _David W. Wilson_