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 A094115 #5 Mar 30 2012 18:39:22 %S A094115 0,1,1,4,6,9,9,10,10,19,27,36,42,49,55,64,72,81,81,82,82,85,87,90,90, %T A094115 91,91,118,144,171,195,220,244,271,297,324,342,361,379,400,420,441, %U A094115 459,478,496,523,549,576,600,625,649,676,702,729,729,730,730,733,735,738,738 %N A094115 Partial sums of A093347. %F A094115 a(3^k)=(9^k-1)/8 %o A094115 (PARI) a(n)=sum(k=1,n,-sum(i=1,k-1,(-1)^i*3^valuation(i,3))) %K A094115 nonn %O A094115 1,4 %A A094115 _Benoit Cloitre_, May 03 2004