A283021 Erroneous version of A263656.

0, 2, 4, 6, 12, 30, 70, 168, 412, 1014, 2514, 6270, 15702, 39468, 99516, 251586, 637500

Offset: 0

Author

Andrew Howroyd, Feb 26 2017

Keywords

• dead

Comments

Included in accordance with OEIS policy of including erroneous but published sequences to serve as pointers to the correct versions.

Number of length-2n central circular binary strings without zigzags (see reference for precise definition).

Differs from A263656 at only a(1).

See page 6, "Central strings", which gives this almost certainly incorrect sequence.

Compare with leading diagonal of Fig 1 (which is A253656)

[The other possible rationale for this discrepanncy would be that this sequence also counts the strings 01 and 10. However these are excluded from the other sequences and formula in the same paper.]

Links

• E. Munarini and N. Z. Salvi, Circular Binary Strings without Zigzags, Integers: Electronic Journal of Combinatorial Number Theory 3 (2003), #A19.

Crossrefs

Cf. A263656.