Circular Logic II (noch nicht übersetzt)
Problem 703
Given an integer n, n≥3, let B={false,true} and let Bn be the set of sequences of n values from B. The function f from Bn to Bn is defined by f(b1…bn)=c1…cn where:
- ci=bi+1 for 1≤i<n.
- cn=b1AND(b2XORb3), where AND and XOR are the logical AND and exclusive OR operations.
Let S(n) be the number of functions T from Bn to B such that for all x in Bn, T(x) AND T(f(x))=false. You are given that S(3)=35 and S(4)=2118.
Find S(20). Give your answer modulo 1001001011.