OFFSET
1,2
COMMENTS
First differs from A093811 at a(21) = 12.
Inverse Möbius transform of (n mod 10) (A010879). - Wesley Ivan Hurt, Jun 23 2024
FORMULA
a(n) = Sum_{d|n} (d mod 10).
EXAMPLE
a(21) = 12; The divisors of 21 are {1, 3, 7, 21} and the sum of the final digits of the divisors is 1 + 3 + 7 + 1 = 12.
MAPLE
f:= proc(n) add(t mod 10, t = numtheory:-divisors(n)) end proc:
map(f, [$1..100]); # Robert Israel, Nov 19 2023
MATHEMATICA
Table[DivisorSum[n, Mod[#, 10] &], {n, 100}]
PROG
(PARI) a(n) = sumdiv(n, d, d%10); \\ Michel Marcus, Nov 19 2023
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
Wesley Ivan Hurt, Nov 18 2023
STATUS
approved