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Indices of terms in A093019 with value 3.
1

%I #15 Aug 17 2021 07:18:44

%S 8,13,27,32,46,51,65,70,89,94,107,112,126,131,145,150,169,174,188,193,

%T 206,211,225,230,249,254,268,273,287,292,305,310,329,334,348,353,367,

%U 372,386,391,409,414,428,433,447,452,466,471,485,490,503,517,522,536

%N Indices of terms in A093019 with value 3.

%C Integers which require a following 3 to have a valid Luhn mod 10 check digit.

%H Reinhard Zumkeller, <a href="/A093023/b093023.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)) = 3. - _Reinhard Zumkeller_, Nov 08 2014

%e 13 is in the sequence because A093019(13)=3; 133 has a valid Luhn mod 10 check digit.

%o (Haskell)

%o a093023 n = a093023_list !! (n-1)

%o a093023_list = filter ((== 3) . 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