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 A247023 #20 Sep 20 2014 09:46:24 %S A247023 1,2,1,4,3,1,8,8,4,1,16,21,13,5,1,32,56,40,19,6,1,64,154,122,66,26,7, %T A247023 1,128,440,376,222,100,34,8,1,256,1309,1181,741,365,143,43,9,1,512, %U A247023 4048,3792,2483,1302,561,196,53,10,1,1024,12958,12446,8398,4606 %N A247023 Riordan array (1/(1-2*x), x*C(x)) where C(x) is the o.g.f. of Catalan numbers A000108. %C A247023 Row sums are A014318. %C A247023 Mirror image of the triangle in A201634. %H A247023 Reinhard Zumkeller, <a href="/A247023/b247023.txt">Rows n = 0..125 of triangle, flattened</a> %F A247023 T(n,0) = 2^n = A000079(n). %F A247023 T(n+1,1) = A014318(n). %e A247023 Triangle begins %e A247023 1 %e A247023 2, 1 %e A247023 4, 3, 1 %e A247023 8, 8, 4, 1 %e A247023 16, 21, 13, 5, 1 %e A247023 32, 56, 40, 19, 6, 1 %e A247023 64, 154, 122, 66, 26, 7, 1 %e A247023 Production matrix begins %e A247023 2, 1 %e A247023 0, 1, 1 %e A247023 0, 1, 1, 1 %e A247023 0, 1, 1, 1, 1 %e A247023 0, 1, 1, 1, 1, 1 %e A247023 0, 1, 1, 1, 1, 1, 1 %e A247023 0, 1, 1, 1, 1, 1, 1, 1 %o A247023 (Haskell) %o A247023 a247023 n k = a247023_tabl !! n !! k %o A247023 a247023_row n = a247023_tabl !! n %o A247023 a247023_tabl = map reverse a201634_tabl %o A247023 -- _Reinhard Zumkeller_, Sep 20 2014 %Y A247023 Cf. A000079, A000108, A014318, A201634. %K A247023 nonn,tabl %O A247023 0,2 %A A247023 _Philippe Deléham_, Sep 13 2014 %E A247023 Data corrected by _Reinhard Zumkeller_, Sep 20 2014