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 A245426 #8 Jul 22 2014 12:36:03 %S A245426 7,7,14,21,42,70,126,217,378,665,1162,2037,3563,6237,10913,19096, %T A245426 33418,58485,102347,179109,313439,548520,959910,1679839,2939720, %U A245426 5144510,9002889,15755061,27571355,48249873,84437276,147765233,258589156,452531023,791929292 %N A245426 Number of nonnegative integers with property that their base 7/4 expansion (see A024641) has n digits. %e A245426 The numbers 7-13 are represented by 40, 41, 42, 43, 44, 45, 46 respectively in base 7/4. These are the only integers with two digits, and so a(2)=7. %o A245426 (Sage) %o A245426 A=[1] %o A245426 for i in [1..60]: %o A245426 A.append(ceil((7-4)/4*sum(A))) %o A245426 [7*x for x in A] %Y A245426 Cf. A024641, A081848. %K A245426 nonn,base %O A245426 1,1 %A A245426 _James Van Alstine_, Jul 21 2014