A202967 Number of arrays of 7 integers in -n..n with sum zero and adjacent elements differing in absolute value

6, 524, 9872, 66208, 289536, 941086, 2537024, 5933492, 12515772, 24295760, 44188086, 76110890, 125357152, 198686606, 304811136, 454458544, 660981870, 940393644, 1312104510, 1798910920, 2427885688, 3230300850, 4242680088

Offset

1,1

Comments

Row 5 of A202962

Links

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

Formula

Empirical: a(n) = 2*a(n-1) -a(n-2) +a(n-3) -2*a(n-5) +a(n-6) -3*a(n-7) +3*a(n-8) -a(n-9) +2*a(n-10) +a(n-11) -a(n-13) -2*a(n-14) +a(n-15) -3*a(n-16) +3*a(n-17) -a(n-18) +2*a(n-19) -a(n-21) +a(n-22) -2*a(n-23) +a(n-24)

Example

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

Crossrefs

Sequence in context: A222607 A000411 A180431 * A230330 A252174 A251697

Adjacent sequences: A202964 A202965 A202966 * A202968 A202969 A202970

Keyword

nonn

Author

R. H. Hardin Dec 26 2011

Status

approved