A202504 Number of zero-sum -1..1 arrays of n elements with first through third differences also in -1..1.

1, 1, 3, 1, 5, 9, 7, 11, 13, 13, 23, 27, 39, 57, 73, 109, 149, 209, 305, 423, 615, 877, 1249, 1807, 2575, 3709, 5339, 7659, 11065, 15915, 22957, 33137, 47781, 69037, 99707, 144055, 208353, 301197, 435875, 630727, 913071, 1322233, 1915221, 2774755

Offset

1,3

Comments

Column 1 of A202511.

Links

R. H. Hardin, Table of n, a(n) for n = 1..210

Example

All solutions for n=7
.-1....1....0....1....0....0...-1
..0....1....1....0....0...-1...-1
..0....1....1....0....0...-1...-1
..0....0....0....0....0....0....0
..0...-1...-1....0....0....1....1
..0...-1...-1....0....0....1....1
..1...-1....0...-1....0....0....1

Crossrefs

Cf. A202511.

Sequence in context: A215456 A225855 A201751 * A146916 A146255 A331432

Adjacent sequences: A202501 A202502 A202503 * A202505 A202506 A202507

Keyword

nonn

Author

R. H. Hardin, Dec 20 2011

Status

approved