This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A116667 #10 Apr 13 2024 22:52:47 %S A116667 9,9,9,9,9,9,9,9,9,8,9,9,9,9,9,9,9,9,9,8,9,9,9,9,9,9,9,9,9,8,9,9,9,9, %T A116667 9,9,9,9,9,8,9,9,9,9,9,9,9,9,9,8,9,9,9,9,9,9,9,9,9,8,9,9,9,9,9,9,9,9, %U A116667 9,8,9,9,9,9,9,9,9,9,9,8,9,9,9,9,9,9,9,9,9,7,8,8,8,8,8,8,8,8,7,8,9,9,9,9,9 %N A116667 Greatest digit not used in n (or 10 if n is pandigital). %C A116667 a(A050278(1)) = a(1023456789) = 10, the first term with that value, as 1023456789 is the first base 10 pandigital number. %H A116667 Alois P. Heinz, <a href="/A116667/b116667.txt">Table of n, a(n) for n = 0..10000</a> %e A116667 a(89) = 7 because decimal digits 8 and 9 are both used in 89. %o A116667 (Python) %o A116667 def A116667(n): %o A116667 s = set(str(n)) %o A116667 for i in range(9,-1,-1): %o A116667 if str(i) not in s: %o A116667 return i %o A116667 return 10 # _Chai Wah Wu_, Apr 13 2024 %Y A116667 Cf. A067898 (least digit not used in n), A050278 (pandigital numbers). %K A116667 base,easy,nonn %O A116667 0,1 %A A116667 _Rick L. Shepherd_, Feb 22 2006