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 A077268 #10 Dec 07 2019 12:18:24 %S A077268 0,1,1,2,2,3,1,3,3,4,3,5,2,3,3,4,3,6,4,6,4,3,2,7,3,4,5,7,4,7,2,6,5,5, %T A077268 6,8,4,5,5,8,3,7,2,5,6,4,3,9,4,7,7,7,4,9,6,8,4,4,3,11,3,4,5,7,7,9,4,6, %U A077268 6,9,4,11,5,6,8,7,7,9,4,9,6,6,5,12,6,5,5,9,4,11,5,6,4,4,5,11,4,7,8,10,6 %N A077268 Number of bases in which n requires at least one zero to be written. %H A077268 Eric M. Schmidt, <a href="/A077268/b077268.txt">Table of n, a(n) for n = 1..10000</a> %e A077268 a(9)=3 since it requires zeros when written in bases 2, 3 or 9 (as 1001, 100 or 10 respectively). %o A077268 (Sage) def A077268(n) : return sum(0 in n.digits(m) for m in range(2,n+1)) # _Eric M. Schmidt_, Jul 09 2014 %o A077268 (PARI) a(n) = sum(i=2, n, ! vecmin(digits(n, i))); \\ _Michel Marcus_, Jul 09 2014 %Y A077268 Cf. A033093, A062842, A077266, A077267. %K A077268 base,nonn %O A077268 1,4 %A A077268 _Henry Bottomley_, Nov 01 2002