cp's OEIS Frontend

A202816 The left-hand half-triangle of A185356 (or A202690).

%I A202816 #12 Jun 03 2020 03:45:09
%S A202816 1,1,0,3,4,4,11,8,4,0,57,68,76,80,80,361,304,236,160,80,0,2763,3124,
%T A202816 3428,3664,3824,3904,3904,24611,21848,18724,15296,11632,7808,3904,0,
%U A202816 250737,275348,297196,315920,331216,342848,350656,354560,354560
%N A202816 The left-hand half-triangle of A185356 (or A202690).
%H A202816 M. Josuat-Vergès, J.-C. Novelli and J.-Y. Thibon, <a href="http://arxiv.org/abs/1110.5272">The algebraic combinatorics of snakes</a>, arXiv preprint arXiv:1110.5272 [math.CO], 2011.
%e A202816 Triangle begins:
%e A202816     1
%e A202816     1   0
%e A202816     3   4   4
%e A202816    11   8   4   0
%e A202816    57  68  76  80 80
%e A202816   361 304 236 160 80 0
%e A202816   ...
%o A202816 (PARI) T(n,k) = {if ((k==0), return(0)); if (n==1, if (abs(k)==1, return(1))); if (n%2, if (k<0, sum(j=k+1, n-1, T(n-1,j)), sum(j=k, n-1, T(n-1,j))), if (k<0, sum(j=-n+1, k, T(n-1,j)), sum(j=-n+1, k-1, T(n-1,j))));}
%o A202816 tabl(nn) = {for (n=1, nn, for (k=1, n, if (k, print1(T(n, -k), ", "));); print;);} \\ _Michel Marcus_, Jun 03 2020
%Y A202816 Cf. A185356, A202690, A202815.
%K A202816 nonn,tabl
%O A202816 1,4
%A A202816 _N. J. A. Sloane_, Dec 25 2011
%E A202816 More terms from _Michel Marcus_, Jun 03 2020