A053837 Sum of digits of n modulo 10.

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 1, 2, 3, 4, 5

Offset: 0

Author

Henry Bottomley, Mar 28 2000

Keywords

• base
• nonn
• easy

Examples

			a(59)=4 because 5+9 = 14 = 4 mod 10.
		

Crossrefs

Cf. A007953, A010879.

Cf. A000120, A010060, A053838, A053839, A053840, A053841, A053842, A053843, A053844.

Programs

Mathematica

Table[Mod[Total[IntegerDigits[n]],10],{n,0,120}] (* Harvey P. Dale, Oct 02 2018 *)

PARI

a(n)=sumdigits(n)%10 \\ Charles R Greathouse IV, Feb 02 2023

Formula

a(n) = A010879(A007953(n)) = (n+a(floor[n/10])) mod 10. So can construct sequence by starting with 0 and mapping 0->0123456789, 1->1234567890, 2->2345678901 etc. (e.g. 0, 0123456789, 0123456789123456789023456789013456789012456..., etc.) and looking at n-th digit of a term with sufficient digits.