OFFSET
1,2
LINKS
D. C. Gijswijt, Krulgetallen, Pythagoras, 55ste Jaargang, Nummer 3, Jan 2016. (Shows that the sequence is infinite)
F. J. van de Bult, D. C. Gijswijt, J. P. Linderman, N. J. A. Sloane and Allan Wilks, A Slow-Growing Sequence Defined by an Unusual Recurrence, J. Integer Sequences, Vol. 10 (2007), #07.1.2.
FORMULA
a(n) is about 2^(2^(3^(4^(5^...^(n-1))))).
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, based on a suggestion from Dion Gijswijt (gijswijt(AT)science.uva.nl), Mar 04 2004
EXTENSIONS
Sequence is infinite but next term, about 10^(10^23.09987) (see A091787), is too large to include.
STATUS
approved