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 A270172 #17 Dec 08 2018 03:01:11 %S A270172 0,0,0,0,0,0,0,0,0,0,9,9,9,9,9,9,9,9,9,9,8,8,8,8,8,8,8,8,8,8,7,7,7,7, %T A270172 7,7,7,7,7,7,6,6,6,6,6,6,6,6,6,6,5,5,5,5,5,5,5,5,5,5,4,4,4,4,4,4,4,4, %U A270172 4,4,3,3,3,3,3,3,3,3,3,3,2,2,2,2,2,2,2 %N A270172 Number of steps required to reach a single-digit number when successively increasing all digits of n by 1 simultaneously and removing leading zeros (9 becomes 0). %H A270172 Felix Fröhlich, <a href="/A270172/b270172.txt">Table of n, a(n) for n = 0..10000</a> %e A270172 For n = 11: Successively increasing the digits of n yields the sequence s(t) (starting with t = 0): 11, 22, 33, 44, 55, 66, 77, 88, 99, 0. s(9) = 0, so a(11) = 9. %e A270172 For n = 15: The sequence s(t) (again starting with t = 0): 15, 26, 37, 48, 59, 60, 71, 82, 93, 4. s(9) = 4, so a(15) = 9. %o A270172 (PARI) eva(n) = subst(Pol(n), x, 10) %o A270172 increasedigits(n) = my(d=digits(n)); for(k=1, #d, d[k]++; if(d[k]==10, d[k]=0)); eva(d) %o A270172 a(n) = my(x=n, i=0); while(#Str(x) > 1, x=increasedigits(x); i++); i %Y A270172 Cf. A256079, A270173. %K A270172 nonn,base %O A270172 0,11 %A A270172 _Felix Fröhlich_, Mar 12 2016