A245344 - OEIS

%I #15 May 14 2021 06:35:31

%S 0,1,2,3,4,5,6,3,4,5,6,7,8,9,6,7,8,9,10,11,12,5,6,7,8,9,10,11,8,9,10,

%T 11,12,13,14,7,8,9,10,11,12,13,10,11,12,13,14,15,16,5,6,7,8,9,10,11,8,

%U 9,10,11,12,13,14,11,12,13,14,15,16,17

%N Sum of digits of n written in fractional base 7/3.

%C The base 7/3 expansion is unique, and thus the sum of digits function is well-defined.

%H Alois P. Heinz, <a href="/A245344/b245344.txt">Table of n, a(n) for n = 0..10000</a>

%e In base 7/3 the number 7 is represented by 30 and so a(7) = 3 + 0 = 3.

%p a:= proc(n) `if`(n<1, 0, irem(n, 7, 'q')+a(3*q)) end:

%p seq(a(n), n=0..69);  # _Alois P. Heinz_, May 14 2021

%o (Sage) # uses [basepqsum from A245355]

%o [basepqsum(7,3,y) for y in [0..200]]

%Y Cf. A024640, A053828, A007953.

%K nonn,base

%O 0,3

%A _James Van Alstine_, Jul 18 2014

%E Definition corrected by _Georg Fischer_, May 14 2021