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a(n) = A093018(n) mod 10.
13

%I #16 Aug 17 2021 06:49:14

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

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

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

%N a(n) = A093018(n) mod 10.

%C Luhn mod 10 check digits of terms in A093018.

%H Reinhard Zumkeller, <a href="/A093019/b093019.txt">Table of n, a(n) for n = 0..10000</a>

%H John Kilgo, <a href="https://web.archive.org/web/20040627030859/http://www.dotnetjohn.com/articles/articleid97.aspx">Using the Luhn Algorithm</a>, DotNetJohn.com.

%H Webopedia, <a href="http://www.webopedia.com/TERM/L/Luhn_formula.html">Luhn formula</a>

%H Wikipedia, <a href="http://en.wikipedia.org/wiki/Luhn_algorithm">Luhn algorithm</a>

%H <a href="/index/De#decimal_expansion">Index entries for sequences related to decimal expansion of n</a>

%F a(n) = A093018(n) - 10*n. - _Reinhard Zumkeller_, Nov 08 2014

%e a(1)=8 because A093018(1) mod 10 = 18 mod 10 = 8.

%e a(5)=9 because A093018(5) mod 10 = 59 mod 10 = 9.

%o (Haskell)

%o a093019 = flip mod 10 . a093018 -- _Reinhard Zumkeller_, Nov 08 2014

%Y Cf. A093017-A093029.

%Y Cf. A010879.

%K easy,nonn,base

%O 0,2

%A _Ray Chandler_, Apr 03 2004