

A307406


Number of twisted permutations of the nonnegative integers in base 2*n+1 with an adjacency diagram as defined by Knuth in A220952.


3




OFFSET

0,3


COMMENTS

The concept of the adjacency diagram in A220952 is not limited to base 5, but can be investigated for all odd bases. In "base 1", the path consists of a single node (1,1). For base 3, there is the ternary Gray code A128173 only. A corresponding simple updown pattern with a path (0,0), ... (0,n), (1,n), ... (1,0), (2,0), ... (n,n) can be constructed for any odd base.
Conjecture: a(4) = 673.


LINKS



PROG

(Perl) cf. link


CROSSREFS



KEYWORD

nonn,hard,more


AUTHOR



STATUS

approved



