A143796 - cp's OEIS frontend

A143796 Ackermann function, defined recursively by A(0,n) = n+1, A(m+1,0) = A(m,1), A(m+1,n+1) = A(m,A(m+1,n)) for any nonnegative integers n, m. Table read by antidiagonals, the second term being A(0,1).

n	a(n)
0	1
1	2
2	2
3	3
4	3
5	3
6	4
7	4
8	5
9	5
10	5
11	5
12	7
13	13
14	13
15	6
16	6
17	9
18	29
19	65533
20	65533
21	7
22	7
23	11
24	61

[1, 2, 2, 3, 3, 3, 4, 4, 5, 5, 5, 5, 7, 13, 13, 6, 6, 9, 29, 65533, 65533, 7, 7, 11, 61]