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 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). 2
 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 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Also known as Ackermann-Peter function. The next term is 2^65536-3. This is a computable function that is not primitive recursive. REFERENCES R. Peter, Rekursive Funktionen in der Komputer-Theorie. Budapest: Akad. Kiado, 1951. LINKS W. Ackermann, Zum Hilbertschen Aufbau der reellen Zahlen, Math. Ann. 99 (1928), 118-133. R. C. Buck, Mathematical induction and recursive definitions, Amer. Math. Monthly, 70 (1963), 128-135. E. Weisstein, Mathworld, Ackermann function. Wikipedia, Ackermann function. FORMULA A(1,n) = 2+(n+3) - 3 = n + 2. A(2,n) = 2*(n+3) - 3 = 2n + 3. A(3,n) = 2^(n+3) - 3. A(4,n) = 2^^(n+3)- 3 (a power tower of n+3 two's). CROSSREFS A046859(n)=A(n, n), A126333(n)=A(n, 0). Cf. A143797. Sequence in context: A274533 A163127 A077113 * A245473 A306904 A057362 Adjacent sequences:  A143793 A143794 A143795 * A143797 A143798 A143799 KEYWORD nonn,tabl AUTHOR Benoit Jubin, Sep 01 2008 STATUS approved

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Last modified May 24 07:31 EDT 2022. Contains 354005 sequences. (Running on oeis4.)