A201084 Number of -4..4 arrays of n elements with first and second differences also in -4..4

9, 61, 323, 1759, 9593, 52401, 286207, 1563111, 8536807, 46623423, 254632457, 1390667451, 7595086541, 41480325457, 226543492197, 1237260160029, 6757257460559, 36904549131343, 201553034567103, 1100775560224471

Offset

1,1

Comments

Column 4 of A201088

Links

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

Formula

Empirical: a(n) = 6*a(n-1) -2*a(n-2) -9*a(n-3) +27*a(n-4) -25*a(n-5) -48*a(n-6) +46*a(n-7) -7*a(n-8) -47*a(n-9) +49*a(n-10) +54*a(n-11) -16*a(n-12) -21*a(n-13) +10*a(n-14) +21*a(n-15) +9*a(n-16) -11*a(n-17) -9*a(n-18) +2*a(n-19) +3*a(n-20) -5*a(n-22) -3*a(n-23) +2*a(n-24) -a(n-26)

Example

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

Crossrefs

Sequence in context: A172208 A202660 A202120 * A305783 A005060 A125346

Adjacent sequences: A201081 A201082 A201083 * A201085 A201086 A201087

Keyword

nonn

Author

R. H. Hardin Nov 26 2011

Status

approved