[seqfan] Iteration
Yasu Koh
kohmotopp at gmail.com
Wed Dec 21 09:19:45 CET 2022
Hi Se fans
Many years ago , I considered the following iteration
x(n) = [A*x(n-1) + B]/p^k
where [m] is Floor(m), p^k is the highest power of p dividing
[A*x(n-1) + B]
It can strangely represent any degree sequence like Universal Turing
Machin do any computation
I give you four example that re linear , two degree , three degree ,
four degree
1. Linear
{ x(0),p,A,B } = { 1,2,2.00013,3.0 } :
Between 0-th term and 10000-th term, there are 44 linear subsequences
such that 4<={number of terms}.
The first several are
x(16) to x(3613) x(n)=x(n-1)+2
x(3650) to x(3655) x(n)=x(n-1)+1028
x(3820) to x(3848) x(n)=x(n-1)+66
..........
>From a linear part to next linear part , it behaves as if it were a random
sequence
2. Two degree
{ x(0), p, A, B } = { 2443499297,2,2.00014,3.0 } :
The 68 terms from 0-th to 67-th are represented as follows
x(n) = 6*n^2+171040*n+2443499297
3. Three degree
{ x(0),p,A,B } = { 2417903893829791,2,2.00013,3.0 } :
The 5 terms from 0-th term to 4-th term are represented as follows.
x(n) = 664/6*n^3+5107490*n^2+471475936498/3*n+2417903893829791
4. Four degree
{ x(0),p,A,B } = { 2015985557869547951,2,2.00013,3.2 } :
The 8 terms from 0-th term to 7-th term are
2015985557869547951, 2016116596930809473, 2016247644509609977,
2016378700606503103, 2016509765222042527, 2016640838356781961,
2016771920011275153, 2016903010186075887
I am sure polynomial sequence of five degree
Could any one find it ? It might exist on LLI {x0, p, A, B } =
{1, 2, 2.000014, 3.0
Here re more example
https://mixi.jp/view_bbs.pl?comm_id=964735&id=99457040
Yasutoshi
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