0,2

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.

Y. Sundblad, The Ackermann function. A theoretical, computational, and formula manipulative study, Nordisk Tidskr. Informationsbehandling (BIT) 11 (1971), 107-119.

W. Ackermann, Zum Hilbertschen Aufbau der reellen Zahlen, Math. Ann. 99 (1928), 118-133.

Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.

Cf. A014221, A046859.

Sequence in context: A119529 A096847 A011993 this_sequence A019676 A019900 A122791

Adjacent sequences: A001692 A001693 A001694 this_sequence A001696 A001697 A001698

nonn,nice

njas

a(5)=2^2^...^2, with 2^2^...^2 [ with 65536 two's ] two's.