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 A269667 #15 Mar 14 2016 09:49:03 %S A269667 0,9,8,7,6,5,4,3,2,1,10,9,18,17,16,15,14,13,12,11,10,9,8,17,16,15,14, %T A269667 13,12,11,10,9,8,7,16,15,14,13,12,11,10,9,8,7,6,15,14,13,12,11,10,9,8, %U A269667 7,6,5,14,13,12,11,10,9,8,7,6,5,4,13,12,11,10,9,8,7 %N A269667 a(n) = A270172(10*n). %H A269667 Felix Fröhlich, <a href="/A269667/b269667.txt">Table of n, a(n) for n = 0..10000</a> %o A269667 (PARI) eva(n) = subst(Pol(n), x, 10) %o A269667 increasedigits(n) = my(d=digits(n)); for(k=1, #d, d[k]++; if(d[k]==10, d[k]=0)); eva(d) %o A269667 a270172(n) = my(x=n, i=0); while(#Str(x) > 1, x=increasedigits(x); i++); i %o A269667 a(n) = a270172(10*n) %Y A269667 Cf. A270172, A270173. %K A269667 nonn,base %O A269667 0,2 %A A269667 _Felix Fröhlich_, Mar 13 2016