A059510 Main diagonal of the array A059220.

1, 1, 8, 152, 4493, 202066, 12841750, 1097043147, 121284672716, 16850062144162, 2873723485196575, 590279507847844136, 143737044733324878879, 40943428029694983816963, 13488163010054730357533318, 5088553275271661089776406989

Offset: 1

Author

Floor van Lamoen, Jan 21 2001

Keywords

• easy
• nonn

Links

• G. C. Greubel, Table of n, a(n) for n = 1..240

Programs

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 *)

Extensions

Terms a(11) onward added by G. C. Greubel, Sep 10 2017