A339541 a(n) = n + sod(n, sod(n, 10)), where sod(n,b) is the sum of base-b digits of n.

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

Offset: 1

Author

Robert Israel, Dec 08 2020

Keywords

• nonn
• base

Examples

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

Links

• Robert Israel, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A007953, A138530

Programs

Maple

sod:= proc(x,b) if b=1 then x else convert(convert(x,base,b),`+`) fi end proc:
f:= x -> x + sod(x,sod(x,10)):
map(f, [$1..100]);

Formula

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