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 A170952 #3 Mar 30 2012 16:51:55 %S A170952 0,0,1,0,1,3,4,0,1,3,9,12,13,0,1,3,9,10,27,36,39,40,0,1,3,9,27,30,81, %T A170952 85,108,117,120,121,0,1,3,9,27,28,81,90,91,220,243,255,307,324,351, %U A170952 360,363,364,0,1,3,9,27,81,84,175,243,270,273,625,660,729,733,765,921,972,1053 %N A170952 Take the Cantor set sequence A121153 and if the entry m = A121153(n) is in the range 3^k <= m < 3^(k+1), subtract 3^k from it. %H A170952 N. J. A. Sloane, <a href="/A170952/b170952.txt">Table of n, a(n) for n=1..179</a> %e A170952 If written as a triangle: %e A170952 0, %e A170952 0, 1, %e A170952 0, 1, 3, 4, %e A170952 0, 1, 3, 9, 12, 13, %e A170952 0, 1, 3, 9, 10, 27, 36, 39, 40, %e A170952 0, 1, 3, 9, 27, 30, 81, 85, 108, 117, 120, 121, %e A170952 0, 1, 3, 9, 27, 28, 81, 90, 91, 220, 243, 255, 307, 324, 351, 360, 363, 364, %e A170952 0, 1, 3, 9, 27, 81, 84, 175, 243, 270, 273, 625, 660, 729, 733, 765, 921, 972, 1053, 1080, 1089, 1092, 1093, %e A170952 ... %Y A170952 Cf. A121153, A170943, A170944, A170951. %K A170952 nonn,tabf %O A170952 1,6 %A A170952 J. H. Conway, T. D. Noe and _N. J. A. Sloane_, Feb 22 2010