login
a(n) = n + sod(n, sod(n, 10)), where sod(n,b) is the sum of base-b digits of n.
3

%I #7 Dec 08 2020 21:15:31

%S 2,3,4,5,6,7,8,9,10,20,14,14,17,20,20,20,20,20,29,22,24,26,30,28,32,

%T 31,30,38,38,32,38,36,41,44,42,40,47,46,45,44,46,44,50,53,50,56,54,52,

%U 62,52,57,56,64,60,65,62,70,68,66,65,68,75,70,74,80,77,74,84,82,74,79,80,83,88,84,92

%N a(n) = n + sod(n, sod(n, 10)), where sod(n,b) is the sum of base-b digits of n.

%H Robert Israel, <a href="/A339541/b339541.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = n + A138530(n, A007953(n)).

%e a(15) = 15 + 5 = 20 because sod(15,10) = 6 and sod(15,6) = 5 (because 15 = 23_6).

%p sod:= proc(x,b) if b=1 then x else convert(convert(x,base,b),`+`) fi end proc:

%p f:= x -> x + sod(x,sod(x,10)):

%p map(f, [$1..100]);

%Y Cf. A007953, A138530

%K nonn,base

%O 1,1

%A _Robert Israel_, Dec 08 2020