A106307 -id:A106307 - cp's OEIS frontend

A106285 Number of orbits of the 3-step recursion mod n.

1, 4, 3, 12, 5, 12, 9, 44, 21, 20, 25, 36, 15, 66, 15, 172, 53, 84, 21, 60, 27, 144, 23, 132, 105, 116, 183, 482, 177, 60, 91, 684, 75, 420, 45, 252, 109, 162, 45, 220, 125, 198, 265, 520, 105, 92, 2259, 516, 359, 420, 159, 884, 2867, 732, 125, 3714, 63, 1408, 59, 180

Offset: 1

T. D. Noe, May 02 2005

nonn

Consider the 3-step recursion x(k)=x(k-1)+x(k-2)+x(k-3) mod n. For any of the n^3 initial conditions x(1), x(2) and x(3) in Zn, the recursion has a finite period. Each of these n^3 vectors belongs to exactly one orbit. In general, there are only a few different orbit lengths (A106288) for each n. For instance, the orbits mod 8 have lengths of 1, 2, 4, 8, 16. Interestingly, for n=2^k and n=3^k, the number of orbits appear to be A039301 and A054879, respectively.

			Orbits for n=2: {(0,0,0)}, {(1,1,1)}, {(0,1,0), (1,0,1)} and {(0,0,1), (0,1,1), (1,1,0), (1,0,0)}

D. D. Wall, Fibonacci series modulo m, Amer. Math. Monthly, 67 (1960), 525-532.
Eric Weisstein's World of Mathematics, Fibonacci n-Step Number.

Cf. A015134 (orbits of Fibonacci sequences), A106286 (orbits of 4-step sequences), A106287 (orbits of 5-step sequences), A106288 (number of different orbit lengths), A106307 (n producing a simple orbit structure).

A106288 Number of different orbit lengths of the 3-step recursion mod n.

Original entry on oeis.org

1, 3, 2, 4, 2, 6, 3, 5, 3, 6, 4, 8, 3, 6, 4, 6, 3, 9, 3, 8, 6, 8, 2, 10, 3, 5, 4, 8, 3, 12, 2, 7, 8, 5, 6, 12, 2, 6, 6, 10, 3, 12, 3, 11, 6, 6, 3, 12, 5, 9, 6, 7, 3, 12, 8, 9, 6, 6, 2, 16, 3, 6, 7, 8, 6, 16, 2, 6, 4, 12, 2, 15, 3, 6, 6, 8, 10, 10, 3, 12, 5, 5, 3, 16, 6, 7, 6, 14, 2, 18, 6, 8, 4, 6, 6

Offset: 1

T. D. Noe, May 02 2005

nonn

Consider the 3-step recursion x(k)=x(k-1)+x(k-2)+x(k-3) mod n. For any of the n^3 initial conditions x(1), x(2) and x(3) in Zn, the recursion has a finite period. Each of these n^3 vectors belongs to exactly one orbit. In general, there are only a few different orbit lengths for each n. For n=8, there are 5 different lengths: 1, 2, 4, 8 and 16. The maximum possible length of an orbit is A046738(n), the period of the Fibonacci 3-step sequence mod n.

Eric Weisstein's World of Mathematics, Fibonacci n-Step Number.

Cf. A106285 (orbits of 3-step sequences), A106307 (primes that yield a simple orbit structure in 3-step recursions).

cp's OEIS Frontend

A106285 Number of orbits of the 3-step recursion mod n.

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