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 A168151 #12 Feb 06 2025 22:02:04 %S A168151 1,2,1,6,3,1,18,9,4,1,58,29,13,5,1,192,96,44,18,6,1,650,325,151,64,24, %T A168151 7,1,2232,1116,524,228,90,31,8,1,7746,3873,1833,813,333,123,39,9,1, %U A168151 27096,13548,6452,2904,1222,473,164,48,10,1 %N A168151 Riordan array (1/u,(1-u)/2), u=sqrt(1-4x+4*x^3). %C A168151 T(n,0) = A157004(n). %D A168151 Baccherini, D.; Merlini, D.; Sprugnoli, R. Binary words excluding a pattern and proper Riordan arrays. Discrete Math. 307 (2007), no. 9-10, 1021--1037. MR2292531 (2008a:05003). See Example 5.6. - _N. J. A. Sloane_, Mar 25 2014 %F A168151 T(n,0) = 2*T(n,1) for n>0, T(0,0) = 1, T(n,k) = T(n-1,k-1)-T(n-3,k-1)+T(n,k+1). %e A168151 Triangle begins: %e A168151 1 %e A168151 2 1 %e A168151 6 3 1 %e A168151 18 9 4 1 %e A168151 58 29 13 5 1 %e A168151 192 96 44 18 6 1 %e A168151 650 325 151 64 24 7 1 %e A168151 ... %Y A168151 Cf. A025262, A157004. %K A168151 nonn,tabl %O A168151 0,2 %A A168151 _Philippe Deléham_, Nov 19 2009