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 A134562 #4 Nov 13 2014 12:04:15
%S A134562 1,3,2,9,4,5,27,6,7,8,81,10,11,14,17,243,12,13,16,23,26,729,18,15,20,
%T A134562 25,44,53,2187,28,19,22,35,50,71
%N A134562 Array T by antidiagonals: T(n,k) = k-th number whose formal base-3 representation has exactly n terms. ("Formal" means that all the nonzero coefficients are 1's.).
%C A134562 A permutation of the natural numbers. Except for initial terms in some cases, (Row 1) = A000244, (Row 2) = A055235, (Col 1) = A062318. For the analogous base-2 array, see A067576.
%e A134562 11 = 9 + 1 + 1 is the 3rd largest number (after 5 and 7) that has
%e A134562 a 3-term formal base-3 representation.
%e A134562 Northwest corner:
%e A134562 1 3 9 27 81
%e A134562 2 4 6 10 12
%e A134562 5 7 11 13 15
%e A134562 8 14 16 20 22
%Y A134562 Cf. A067576, A000244, A055235, A062318.
%K A134562 nonn,tabl
%O A134562 1,2
%A A134562 _Clark Kimberling_, Nov 01 2007