

A137453


a(0) = 2, a(1) = 9; thereafter, a(n) = a(n1)*a(n2) mod (a(n1)+a(n2)).


1



2, 9, 7, 15, 17, 31, 47, 53, 91, 71, 143, 95, 19, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95, 95
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OFFSET

0,1


COMMENTS

Playing around with different starting pairs, it looks like all starting pairs either end in a loop, or by going to the pair (0,0) which is either a loop or a singularity, depending on whether you take 0 mod 0 as being 0 or undefined. Furthermore, you can go an arbitrarily long time without looping. Take for large a: .., 6*a+6, 6*a, ... The next term is 6*a6, and progressively it goes down the ladder by steps of 6 until it terminates at ..., 18, 12, 6, 0, 0. In a few minutes of searching, the longest sequence I could find which eventually loops without going to zero was the sequence starting with (29,574), which hits 855 at the 79th term and then stays at 855.  Jack Brennan


LINKS

Table of n, a(n) for n=0..66.
Eric Angelini, ModuloPlay
E. Angelini, ModuloPlay [Cached, with permission]


EXAMPLE

2*9 mod 2+9 = 18 mod 11 = 7.


CROSSREFS

Sequence in context: A160439 A245287 A254595 * A063381 A019078 A205384
Adjacent sequences: A137450 A137451 A137452 * A137454 A137455 A137456


KEYWORD

nonn


AUTHOR

Eric Angelini, Jul 07 2008


EXTENSIONS

More terms from Jack Brennen, Jul 07 2008


STATUS

approved



