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 A056888 #22 Feb 14 2015 23:54:25 %S A056888 2,3,2,0,4,1,3,1,1,5,2,2,3,1,0,3,6,2,3,0,0,4,1,3,1,4,1,1,0,1,3,2,3,5, %T A056888 1,1,3,3,2,5,0,3,3,1,1,3,2,2,0,2,1,5,2,1,1,1,1,3,4,5,1,0,1,3,2,1,2,4, %U A056888 5,1,1,2,1,0,1,2,4,1,2,5,0,2,4,3,2,2,1,2,2,2,0,2,3,2,1,5,1,0,4 %N A056888 a(n) = number of k such that sum of digits of 9^k is 9n. %C A056888 Proposed by _Mark Sapir_, Math. Dept., Vanderbilt University, who remarks (August 2000) that he can prove that a(n) is always finite and that a(1) = 2. %C A056888 Values of a(n) for n>1 computed numerically by _Michael Kleber_, Sep 02 2000 and _David W. Wilson_, Sep 06 2000. %C A056888 All terms except the first are only conjectures. For the theorem that a(n) is always finite, see Senge-Straus and Stewart. - _N. J. A. Sloane_, Jan 06 2011 %D A056888 H. G. Senge and E. G. Straus, PV-numbers and sets of multiplicity, Periodica Math. Hungar., 3 (1971), 93-100. %D A056888 C. L. Stewart, On the representation of an integer in two different bases, J. Reine Angew. Math., 319 (1980), 63-72. %e A056888 There are two powers of 9 with digit-sum 9, namely 9 and 81, so a(1) = 2. %Y A056888 Cf. A065999. %K A056888 nonn,base %O A056888 1,1 %A A056888 _N. J. A. Sloane_, Sep 05 2000