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Indices of terms in A093019 with value 5.
2

%I #15 Aug 17 2021 07:03:44

%S 7,12,26,31,45,50,69,74,88,93,106,111,125,130,149,154,168,173,187,192,

%T 205,210,229,234,248,253,267,272,286,291,309,314,328,333,347,352,366,

%U 371,385,390,408,413,427,432,446,451,465,470,489,494,502,516,521,535

%N Indices of terms in A093019 with value 5.

%C Integers which require a following 5 to have a valid Luhn mod 10 check digit.

%H Reinhard Zumkeller, <a href="/A093025/b093025.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)) = 5. - _Reinhard Zumkeller_, Nov 08 2014

%e 12 is in the sequence because A093019(12)=5; 125 has a valid Luhn mod 10 check digit.

%o (Haskell)

%o a093025 n = a093025_list !! (n-1)

%o a093025_list = filter ((== 5) . 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