A209028 Number of n-bead necklaces labeled with numbers -4..4 allowing reversal, with sum zero and first differences in -4..4.

1, 3, 5, 23, 88, 471, 2517, 14611, 86014, 519574, 3177405, 19681214, 123050881, 775868013, 4926859869, 31483531830, 202298489710, 1306289630067, 8472236548514, 55167003603285, 360512087413974, 2363623888860990, 15542899182846478, 102488033365084376

Offset

1,2

Links

Andrew Howroyd, Table of n, a(n) for n = 1..100

Example

Some solutions for n=6:
.-1...-1...-3...-2...-1...-2...-4...-1...-1...-3...-3...-2...-2...-2...-3...-2
..0...-1...-3....0...-1....1....0...-1....0...-1...-1....0...-1....1...-1....0
.-1...-1...-1...-1...-1....1....2....0...-1....0....2....0...-1...-1....2....3
..1....0....2....2....0...-2....0....0....1....3...-1....0....1....2....0...-1
..0....1....4...-1....3....1....2....0...-1....0....3....2....2...-1....1...-1
..1....2....1....2....0....1....0....2....2....1....0....0....1....1....1....1

Crossrefs

Column 4 of A209032.

Sequence in context: A153410 A230080 A155778 * A178068 A018978 A100703

Adjacent sequences: A209025 A209026 A209027 * A209029 A209030 A209031

Keyword

nonn

Author

R. H. Hardin, Mar 04 2012

Extensions

a(17)-a(24) from Andrew Howroyd, Mar 19 2017

Status

approved