A245335 - OEIS

%I #24 Aug 11 2023 09:54:29

%S 0,1,2,3,4,4,5,6,7,8,7,8,9,10,11,9,10,11,12,13,10,11,12,13,14,10,11,

%T 12,13,14,14,15,16,17,18,13,14,15,16,17,16,17,18,19,20,14,15,16,17,18,

%U 16,17,18,19,20,20,21,22,23,24,17,18,19,20,21,18,19,20,21

%N Sum of digits of n in fractional base 5/4.

%C The base 5/4 expansion is unique and thus the sum of digits function is well-defined.

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

%F a(n) = A007953(A024634(n)). - _Kevin Ryde_, Aug 11 2023

%e In base 5/4 the number 7 is represented by 42 and so a(7)=4+2=6.

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

%o [basepqsum(5,4,y) for y in [0..200]]

%o (PARI) a(n) = my(ret=0,r); while(n, [n,r]=divrem(n,5); ret+=r; n<<=2); ret; \\ _Kevin Ryde_, Aug 11 2023

%Y Cf. A024634, A007953, A053824.

%K nonn,base,easy

%O 0,3

%A _James Van Alstine_, Jul 18 2014