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Indices of terms in A093019 with value 4.
1

%I #15 Aug 17 2021 07:19:33

%S 3,17,22,36,41,55,60,79,84,98,102,116,121,135,140,159,164,178,183,197,

%T 201,215,220,239,244,258,263,277,282,296,300,319,324,338,343,357,362,

%U 376,381,395,404,418,423,437,442,456,461,475,480,499,507,512,526,531

%N Indices of terms in A093019 with value 4.

%C Integers which require a following 4 to have a valid Luhn mod 10 check digit.

%H Reinhard Zumkeller, <a href="/A093024/b093024.txt">Table of n, a(n) for n = 1..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 A093019(a(n)) = 4. - _Reinhard Zumkeller_, Nov 08 2014

%e 17 is in the sequence because A093019(17)=4; 174 has a valid Luhn mod 10 check digit.

%o (Haskell)

%o a093024 n = a093024_list !! (n-1)

%o a093024_list = filter ((== 4) . a093019) [0..]

%o -- _Reinhard Zumkeller_, Nov 08 2014

%Y Cf. A093017-A093029.

%K easy,nonn,base

%O 1,1

%A _Ray Chandler_, Apr 03 2004

%E Offset changed by _Reinhard Zumkeller_, Nov 08 2014