OFFSET
1,3
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..240
MATHEMATICA
t[0, 0] = 1; t[0, _?EvenQ] = 0; t[_?OddQ, 0] = 0; t[n_, k_] /; OddQ[n + k] (*up*):= t[n, k] = t[n + 1, k - 1] + Sum[t[n, j], {j, 0, k - 1}];
t[n_, k_] /; EvenQ[n + k] (*down*):= t[n, k] = t[n - 1, k + 1] + Sum[t[j, k], {j, 0, n - 1}]; Table[t[n, n], {n, 0, 50}] (* G. C. Greubel, Sep 10 2017 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Floor van Lamoen, Jan 21 2001
EXTENSIONS
Terms a(11) onward added by G. C. Greubel, Sep 10 2017
STATUS
approved