A202000 Number of -2..2 circular arrays x(0..n+1) of n+2 elements with zero sums of x(i) and x(i)*x((i+1) mod (n+2))

1, 25, 31, 247, 799, 4281, 15751, 61581, 267037, 1298599, 5618731, 25891377, 121559461, 569107129, 2632371325, 12330807475, 58079266349, 275266138925, 1306176923689, 6218631031361, 29703202000153, 142156751690535

Offset

1,2

Comments

Column 2 of A202006

Links

R. H. Hardin, Table of n, a(n) for n = 1..119

Example

Some solutions for n=7
..2....0....2....2...-2....0....0....2...-2...-1....0...-1....0...-2....1....0
..1....1....2....1....2....1....1....1...-2...-1....0....2....0....2....1....1
.-2....2...-1....2....1....1...-1...-2...-1...-1....0....2....0....1....1....0
..0....0...-2....0...-2...-1...-1....0....1....0....1...-2....2....1....0....0
.-2...-2....2....0....0...-1....0....2....2...-1...-1...-1....0...-1...-2....0
..0....1...-1...-2....0....0....2...-2...-2....1...-1....1....0...-2....1....0
..1....0...-1...-2....2....1....0...-1....2...-1....0....0....1....1...-2....1
.-1...-2...-1....1....1....1....0...-1....1....2....0....0...-2....2...-2...-1
..1....0....0...-2...-2...-2...-1....1....1....2....1...-1...-1...-2....2...-1

Crossrefs

Sequence in context: A039323 A043146 A043926 * A118669 A092100 A172007

Adjacent sequences: A201997 A201998 A201999 * A202001 A202002 A202003

Keyword

nonn

Author

R. H. Hardin Dec 07 2011

Status

approved