A065881 Ultimate modulo 10: right-hand nonzero digit of n.

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

Offset: 1

Author

Henry Bottomley, Nov 26 2001

Keywords

• base
• nonn

Examples

			a(3)=3, a(23)=3, a(30)=3, a(12300)=3.
		

Links

• Harry J. Smith, Table of n, a(n) for n = 1..1000
• Index entries for sequences related to final digits of numbers

Crossrefs

In base 2 this is A000012, base 3 A060236 and base 4 A065882. For n <= 100 this sequence is also "Remove final zeros from n" which in bases 2, 3 and 4 produces A000265, A038502 and A065883. Cf. A010879.

Programs

Mathematica

um10[n_]:=Module[{idns=Split[IntegerDigits[n]]},If[idns[[-1,1]] == 0, idns[[-2,1]], idns[[-1,1]]]]; Array[um10,110] (* Harvey P. Dale, Dec 26 2016 *)

PARI

a(n) = { n/10^valuation(n,10)%10 } \\ Harry J. Smith, Nov 03 2009

Python

def A065881(n): return int(str(n).rstrip('0')[-1]) # Chai Wah Wu, Dec 07 2023

Formula

If n mod 10 = 0 then a(n) = a(n/10), otherwise a(n) = n mod 10.