A201807 Number of arrays of n integers in -4..4 with sum zero and equal numbers of elements greater than zero and less than zero

1, 9, 25, 313, 1401, 15681, 90609, 909945, 6105913, 57290209, 421304049, 3799765201, 29595440785, 261111392985, 2109792275145, 18400232046585, 152275971653625, 1320864136716225, 11107129707193809, 96160509723165393

Offset

1,2

Comments

Column 4 of A201811

Links

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

Example

Some solutions for n=7
.-3....0...-1....4...-2...-4....4...-2....4....4...-3....2....4...-4....1....2
..0....2....2...-4...-2...-4...-4...-1....0....0....0...-4....0...-4...-3...-3
.-4...-4....1...-4....2....4...-3...-4...-3...-4...-2....3....2...-2....1...-4
..2...-2....0....0....2....0....0....2...-2....1....4...-3...-4....0...-1....0
.-2....4....3...-2...-1....3...-2....4....3...-3...-4....4....4....2....4...-2
..4....1...-1....3....1...-3....4....0....1...-2....3...-2...-2....4...-2....4
..3...-1...-4....3....0....4....1....1...-3....4....2....0...-4....4....0....3

Crossrefs

Sequence in context: A193065 A278911 A330828 * A228465 A048056 A038534

Adjacent sequences: A201804 A201805 A201806 * A201808 A201809 A201810

Keyword

nonn

Author

R. H. Hardin Dec 05 2011

Status

approved