A307406 Number of twisted permutations of the nonnegative integers in base 2*n+1 with an adjacency diagram as defined by Knuth in A220952.

1, 1, 5, 47

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 up-down 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

Table of n, a(n) for n=0..3.

Georg Fischer, Repository of programs for related sequences, (gen_paths.pl)

Prog

(Perl) cf. link

Crossrefs

Cf. A128173 (base 3, "n"), A220952 (Knuth, base 5, "Hn"), A307403 ("Hs"), A307404 ("Ln"), A307405 ("Ls"), A300857 (base 7).

Sequence in context: A299715 A377005 A000872 * A060392 A196160 A136088

Adjacent sequences: A307403 A307404 A307405 * A307407 A307408 A307409

Keyword

nonn,hard,more

Author

Georg Fischer, Apr 07 2019

Status

approved