A235938 Number of circular permutations with exactly one specified increasing or decreasing modular run (3-sequence), with clockwise and counterclockwise traversals counted as distinct.

0, 0, 0, 0, 2, 4, 22, 124, 816, 6112, 51642, 485604, 5034606, 57080204, 702766384, 9339630016, 133281949954, 2033044422948, 33014191980502, 568686463073484, 10357838456504880

Offset: 1

Author

Paul J. Campbell, Jan 20 2014, with Joe Marasco and Ashish Vikram

Keywords

• nonn

Examples

			With specified sequence 123:
a(5) = 2: 12354, 32154.
a(6) = 4: 123564, 321564, 123645, 321546.
		

References

• Paul J. Campbell, Circular permutations with exactly one modular run (3-sequence), submitted to Journal of Integer Sequences

Links

• Wayne M. Dymáček and Isaac Lambert, Circular permutations avoiding runs of i, i+1, i+2 or i, i-1, i-2, Journal of Integer Sequences, Vol. 14 (2011) Article 11.1.6.

Crossrefs

Cf. A165961, A165964, A165962, A078628, A078673.

Cf. A235937, A235939, A235940, A235941, A235942, A235943.

Formula

a(n) = 2*A235937(n).

Extensions

a(20)-a(21) from Alois P. Heinz, Jan 24 2014

Obsolete b-file deleted by N. J. A. Sloane, Jan 05 2019