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A177824
a(n) = (Fibonacci(n)*Fibonacci(n+7)) mod 7.
0
0, 0, 6, 5, 1, 6, 2, 1, 0, 0, 6, 5, 1, 6, 2, 1, 0, 0, 6, 5, 1, 6, 2, 1, 0, 0, 6, 5, 1, 6, 2, 1, 0, 0, 6, 5, 1, 6, 2, 1, 0, 0, 6, 5, 1, 6, 2, 1, 0, 0, 6, 5, 1, 6, 2, 1, 0, 0, 6, 5, 1, 6, 2, 1, 0, 0, 6, 5, 1, 6, 2, 1, 0, 0, 6, 5, 1, 6, 2, 1, 0, 0, 6, 5, 1, 6, 2, 1, 0, 0, 6, 5, 1, 6, 2, 1
OFFSET
0,3
COMMENTS
The function f(k,n) = (Fibonacci(n)*Fibonacci(n+k)) mod k appears to be periodic. The repeated values for successive values of k are
k=2...[0,0,1]
k=3...[0,2,1,0]
k=4...[0,1,0,2,3,2]
k=5...[3,3,2,2,0,2,2,3,3,0]
k=6...[0,1,3,2,3,1,0,5,3,4,3,5]
k=7...[0,0,6,5,1,6,2,1]
k=8...[0,2,7,2,0,5]
k=9...[0,1,8,0,6,4,2,6,3,7,5,3]
k=10..[0,9,4,6,1,0,6,1,4,4,5,4,4,1,6,0,1,6,4,9,0,4,9,6,6,5,6,6,9,4]
Periodicity of 8.
MAPLE
with(combinat):
seq((fibonacci(n)*fibonacci(n+7)) mod 7, n=0..50);
MATHEMATICA
Table[Mod[Fibonacci[n]Fibonacci[n+7], 7], {n, 0, 100}] (* Harvey P. Dale, Oct 01 2017 *)
CROSSREFS
Sequence in context: A320833 A216582 A340543 * A242000 A238181 A197517
KEYWORD
nonn
AUTHOR
Gary Detlefs, Dec 13 2010
STATUS
approved