A201872 Number of zero-sum -7..7 arrays of n elements with first and second differences also in -7..7

1, 7, 57, 431, 3373, 27647, 232969, 1990383, 17103271, 147612131, 1278588895, 11110113949, 96822737023, 846090334081, 7411911618255, 65073276474339, 572430700911207, 5044195360234563, 44516912275192801, 393415480687909671

Offset

1,2

Comments

Column 7 of A201873

Links

R. H. Hardin, Table of n, a(n) for n = 1..208

Example

Some solutions for n=6
..6...-1....3....0....0....1....7...-3....4....0....5...-1....5....4....6....0
..1...-2....2...-1....1...-2....5...-3....5....1....4...-5....1...-1...-1....5
.-1...-3...-2....0....0...-2....0...-1....0....1....3...-2....2....1...-3....4
..2...-1....1....1...-3...-1...-3...-1....0....1....0....0...-2....3...-1...-2
.-2....3....0....0...-1...-1...-4....2...-4...-3...-5....1...-4...-1...-2...-1
.-6....4...-4....0....3....5...-5....6...-5....0...-7....7...-2...-6....1...-6

Crossrefs

Sequence in context: A201438 A202510 A042187 * A218587 A218838 A082310

Adjacent sequences: A201869 A201870 A201871 * A201873 A201874 A201875

Keyword

nonn

Author

R. H. Hardin Dec 06 2011

Status

approved