A024641 - OEIS

%I #14 Jul 31 2025 03:51:27

%S 0,1,2,3,4,5,6,40,41,42,43,44,45,46,410,411,412,413,414,415,416,450,

%T 451,452,453,454,455,456,4120,4121,4122,4123,4124,4125,4126,4160,4161,

%U 4162,4163,4164,4165,4166,4530,4531,4532,4533,4534,4535,4536,41200,41201

%N n written in fractional base 7/4.

%C 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 Amiram Eldar, <a href="/A024641/b024641.txt">Table of n, a(n) for n = 0..10000</a>

%H <a href="/index/Ba#base_fractional">Index entries for sequences related to fractional bases</a>.

%t 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 (PARI) a(n) = if(n == 0, 0, 10 * a(n\7 * 4) + n % 7); \\ _Amiram Eldar_, Jul 31 2025

%Y Cf. A245349.

%K nonn,base,easy

%O 0,3

%A _David W. Wilson_