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Indices of terms in A093019 with value 2.
1

%I #15 Aug 17 2021 07:13:04

%S 4,18,23,37,42,56,61,75,80,99,103,117,122,136,141,155,160,179,184,198,

%T 202,216,221,235,240,259,264,278,283,297,301,315,320,339,344,358,363,

%U 377,382,396,400,419,424,438,443,457,462,476,481,495,508,513,527,532

%N Indices of terms in A093019 with value 2.

%C Integers which require a following 2 to have a valid Luhn mod 10 check digit.

%H Reinhard Zumkeller, <a href="/A093022/b093022.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)) = 2. - _Reinhard Zumkeller_, Nov 08 2014

%e 18 is in the sequence because A093019(18)=2; 182 has a valid Luhn mod 10 check digit.

%o (Haskell)

%o a093022 n = a093022_list !! (n-1)

%o a093022_list = filter ((== 2) . 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