%I #7 Mar 16 2020 18:24:41
%S 0,1,2,3,4,5,6,7,8,9,7,8,9,10,11,12,13,14,15,16,11,12,13,14,15,16,17,
%T 18,19,20,12,13,14,15,16,17,18,19,20,21,19,20,21,22,23,24,25,26,27,28,
%U 17,18,19,20,21,22,23,24,25,26,21,22,23,24,25,26,27,28
%N Sum of digits of n written in fractional base 10/7.
%C The base 10/7 expansion is unique and thus the sum of digits function is well-defined.
%F a(n) = A007953(A024662(n)).
%e In base 10/7 the number 14 is represented by 74 and so a(14) = 7 + 4 = 11.
%o (Sage) # uses [basepqsum from A245355]
%o [basepqsum(10,7,w) for w in [0..200]]
%Y Cf. A007953, A000120, A024662, A244040.
%K nonn,base
%O 0,3
%A _Hailey R. Olafson_, Jul 18 2014