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A200557 Number of -n..n arrays x(0..6) of 7 elements with zero sum and nonzero second differences 1
142, 4978, 43698, 211374, 737460, 2076774, 5012084, 10807826, 21368704, 39388482, 68614738, 114064374, 182196622, 281328582, 421889370, 616590012, 881040966, 1234022180, 1697613488, 2298081194, 3066132222, 4036964078, 5251498784 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 5 of A200553

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..146

FORMULA

Empirical: a(n) = 3*a(n-1) -6*a(n-2) +11*a(n-3) -16*a(n-4) +21*a(n-5) -24*a(n-6) +23*a(n-7) -19*a(n-8) +10*a(n-9) +a(n-10) -13*a(n-11) +25*a(n-12) -34*a(n-13) +40*a(n-14) -41*a(n-15) +37*a(n-16) -28*a(n-17) +14*a(n-18) +3*a(n-19) -20*a(n-20) +34*a(n-21) -42*a(n-22) +42*a(n-23) -34*a(n-24) +20*a(n-25) -3*a(n-26) -14*a(n-27) +28*a(n-28) -37*a(n-29) +41*a(n-30) -40*a(n-31) +34*a(n-32) -25*a(n-33) +13*a(n-34) -a(n-35) -10*a(n-36) +19*a(n-37) -23*a(n-38) +24*a(n-39) -21*a(n-40) +16*a(n-41) -11*a(n-42) +6*a(n-43) -3*a(n-44) +a(n-45)

EXAMPLE

Some solutions for n=3

.-3....2....0...-1...-1....0....0...-1...-1....2....3....1....1...-2...-3....1

..0...-3...-1....0...-3....0...-2....1...-3....2...-2...-1....3....2....3....2

.-3....0....0...-3....1....1...-2...-2....3...-2...-2....1....0....0...-3...-1

..3....0....2...-3....1...-3....3....0....0....0....0...-1....0...-3....2....3

..3...-1....3....3....3....3....3...-1....3....1...-3...-1...-1....1....0...-2

.-2....2...-2....3...-1....2....1....1....0...-2....1....1...-3....2....3...-1

..2....0...-2....1....0...-3...-3....2...-2...-1....3....0....0....0...-2...-2

CROSSREFS

Sequence in context: A200453 A283638 A235457 * A077494 A217142 A306090

Adjacent sequences:  A200554 A200555 A200556 * A200558 A200559 A200560

KEYWORD

nonn

AUTHOR

R. H. Hardin Nov 19 2011

STATUS

approved

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Last modified December 9 17:18 EST 2019. Contains 329879 sequences. (Running on oeis4.)