OFFSET
2,1
LINKS
Max Alekseyev, Table of n, a(n) for n = 2..1000
FORMULA
a(n) = n if n is a power of 2; otherwise a(n) = (2^3^4^5^...^n) mod n = A213013(n). [From Max Alekseyev, Jun 02 2012]
EXAMPLE
2^3^4^5 = 2^3^1024. But 3 == -1 (mod 4), so 3^1024 == 1 (mod 4), so 2^3^1024 == 2^1 (mod 5) since 2^4 == 1 (mod 5). Thus a(5) = 2.
CROSSREFS
KEYWORD
nonn,nice
AUTHOR
N. J. A. Sloane, following a suggestion of J. H. Conway, Apr 02 2004
EXTENSIONS
More terms from Robert Munafo, Apr 11 2004
STATUS
approved