A201490 Number of nX2 zero-sum -2..2 arrays with rows and columns lexicographically nondecreasing

3, 29, 226, 1454, 7815, 36487, 151593, 571539, 1982705, 6399842, 19389074, 55531190, 151238480, 393631919, 983211316, 2365399764, 5498241469, 12382111994, 27080912704, 57644263473, 119645822176, 242563511707

Offset

1,1

Comments

Column 2 of A201496

Links

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

Formula

Empirical: a(n) = 6*a(n-2) +7*a(n-3) -10*a(n-4) -38*a(n-5) -31*a(n-6) +48*a(n-7) +148*a(n-8) +133*a(n-9) -96*a(n-10) -416*a(n-11) -479*a(n-12) -12*a(n-13) +797*a(n-14) +1265*a(n-15) +706*a(n-16) -835*a(n-17) -2315*a(n-18) -2338*a(n-19) -344*a(n-20) +2577*a(n-21) +4244*a(n-22) +3040*a(n-23) -620*a(n-24) -4336*a(n-25) -5478*a(n-26) -3214*a(n-27) +932*a(n-28) +4370*a(n-29) +5360*a(n-30) +3926*a(n-31) +1155*a(n-32) -1908*a(n-33) -4647*a(n-34) -6321*a(n-35) -5666*a(n-36) -1759*a(n-37) +4482*a(n-38) +9788*a(n-39) +10241*a(n-40) +4382*a(n-41) -4896*a(n-42) -11847*a(n-43) -11847*a(n-44) -4896*a(n-45) +4382*a(n-46) +10241*a(n-47) +9788*a(n-48) +4482*a(n-49) -1759*a(n-50) -5666*a(n-51) -6321*a(n-52) -4647*a(n-53) -1908*a(n-54) +1155*a(n-55) +3926*a(n-56) +5360*a(n-57) +4370*a(n-58) +932*a(n-59) -3214*a(n-60) -5478*a(n-61) -4336*a(n-62) -620*a(n-63) +3040*a(n-64) +4244*a(n-65) +2577*a(n-66) -344*a(n-67) -2338*a(n-68) -2315*a(n-69) -835*a(n-70) +706*a(n-71) +1265*a(n-72) +797*a(n-73) -12*a(n-74) -479*a(n-75) -416*a(n-76) -96*a(n-77) +133*a(n-78) +148*a(n-79) +48*a(n-80) -31*a(n-81) -38*a(n-82) -10*a(n-83) +7*a(n-84) +6*a(n-85) -a(n-87)

Example

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

Crossrefs

Sequence in context: A174419 A220548 A153825 * A354402 A135163 A074366

Adjacent sequences: A201487 A201488 A201489 * A201491 A201492 A201493

Keyword

nonn

Author

R. H. Hardin Dec 02 2011

Status

approved