Fibonacci-Like Sequence With Mod
Leroy Quet
qq-quet at mindspring.com
Wed Jun 23 21:16:35 CEST 2004
Let a(0) = a(1) = 1;
Let, for 2 <= m,
a(m) = a(m-1) + a(m-2) (mod m),
where 0 <= a(m) <= m-1.
So, a(m) either equals a(m-1) + a(m-2)
or equals a(m-1) + a(m-2) - m,
depending on if a(m-1)+a(m-2) is < m or is between m and 2m-1.
The sequence begins: 1,1,0,1,1,2,3,5,0,5,5,10,3,0,3,3,6,9,15,5,0,...
(maybe)
And the sequence of m's where a(m) = 0, another interesting sequence,
begins:
2,8,13,20,25,...
(maybe)
What can be said about this sequence?
Does it have a closed form?
Does the second sequence (of m's where a(m) = 0) have a closed form?
Neither of the above sequences seems to be in the EIS.
thanks,
Leroy Quet
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