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 A245347 #18 Aug 02 2025 06:26:51 %S A245347 0,1,2,3,4,5,6,7,3,4,5,6,7,8,9,10,6,7,8,9,10,11,12,13,4,5,6,7,8,9,10, %T A245347 11,7,8,9,10,11,12,13,14,10,11,12,13,14,15,16,17,8,9,10,11,12,13,14, %U A245347 15,11,12,13,14,15,16,17,18,4,5,6,7,8,9,10,11,7,8,9 %N A245347 Sum of digits of n written in fractional base 8/3. %C A245347 The base 8/3 expansion is unique and thus the sum of digits function is well-defined. %H A245347 Amiram Eldar, <a href="/A245347/b245347.txt">Table of n, a(n) for n = 0..10000</a> %H A245347 <a href="/index/Ba#base_fractional">Index entries for sequences related to fractional bases</a>. %F A245347 a(n) = A007953(A024645(n)). %e A245347 In base 8/3 the number 14 is represented by 36 and so a(14) = 3 + 6 = 9. %t A245347 a[n_] := a[n] = If[n == 0, 0, a[3 * Floor[n/8]] + Mod[n, 8]]; Array[a, 100, 0] (* _Amiram Eldar_, Aug 02 2025 *) %o A245347 (Sage) # uses [basepqsum from A245355] %o A245347 [basepqsum(8,3,w) for w in [0..200]] %o A245347 (PARI) a(n) = if(n == 0, 0, a(n\8 * 3) + n % 8); \\ _Amiram Eldar_, Aug 02 2025 %Y A245347 Cf. A000120, A007953, A024645, A053829, A244040. %K A245347 nonn,base,easy %O A245347 0,3 %A A245347 _Hailey R. Olafson_, Jul 18 2014