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 A245429 #10 Jul 22 2014 12:35:39 %S A245429 9,9,9,9,18,18,27,36,45,54,72,90,117,153,198,252,324,414,531,684,882, %T A245429 1134,1458,1872,2412,3096,3978,5121,6579,8460,10881,13986,17982,23121, %U A245429 29727,38223,49140,63180,81234,104445,134280,172647,221976,285399,366939,471780 %N A245429 Number of nonnegative integers with property that their base 9/7 expansion (see A024655) has n digits. %e A245429 a(2) = 9 because 70, 71, 72, 73, 74, 75, 76, 77 and 78 are the base 9/7 expansions for the integers 9, 10, 11, 12, 13, 14, 15, 16 and 17 respectively and these are the only integers with 2 digits. %o A245429 (Sage) %o A245429 A=[1] %o A245429 for i in [1..60]: %o A245429 A.append(ceil(((9-7)/7)*sum(A))) %o A245429 [9*x for x in A] %Y A245429 Cf. A024655, A081848, A245356. %K A245429 nonn,base %O A245429 1,1 %A A245429 _Hailey R. Olafson_, Jul 21 2014