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A250561
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T(n,k)=Number of length n+2 0..k arrays with the sum of second differences multiplied by some arrangement of +-1 equal to zero
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13
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2, 5, 8, 8, 25, 14, 13, 60, 83, 32, 18, 117, 302, 297, 62, 25, 200, 761, 1516, 989, 128, 32, 321, 1648, 5105, 7126, 3113, 254, 41, 480, 3125, 13732, 31525, 30780, 9611, 512, 50, 681, 5446, 31173, 106362, 177421, 127586, 29257, 1022, 61, 940, 8843, 63400, 290909
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OFFSET
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1,1
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COMMENTS
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Table starts
....2......5.......8........13.........18.........25..........32...........41
....8.....25......60.......117........200........321.........480..........681
...14.....83.....302.......761.......1648.......3125........5446.........8843
...32....297....1516......5105......13732......31173.......63400.......117749
...62....989....7126.....31525.....106362.....290909......695890......1486139
..128...3113...30780....177421.....744564....2457921.....6924692.....17094253
..254...9611..127586....937817....4808120...18934449....62245658....176612641
..512..29257..518052...4803653...29723864..137976845...522997696...1688068993
.1022..88503.2085808..24257725..180290280..980389815..4258085394..15526286669
.2048.266769.8367220.121800949.1085927844.6899647449.34261234132.140731044189
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LINKS
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FORMULA
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Empirical for column k:
k=1: a(n) = 2*a(n-1) +a(n-2) -2*a(n-3)
k=2: [order 10] for n>15
Empirical for row n:
n=1: a(n) = 2*a(n-1) -2*a(n-3) +a(n-4); also a quadratic polynomial plus a constant quasipolynomial with period 2
n=2: a(n) = 2*a(n-1) -a(n-2) +2*a(n-3) -4*a(n-4) +2*a(n-5) -a(n-6) +2*a(n-7) -a(n-8); also a cubic polynomial plus a linear quasipolynomial with period 3
n=3: [order 21; also a quartic polynomial plus a linear quasipolynomial with period 60]
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EXAMPLE
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Some solutions for n=5 k=4
..0....0....1....4....4....3....4....0....3....0....1....1....1....3....0....3
..1....2....2....0....0....0....4....1....2....4....0....1....2....0....0....3
..3....2....0....3....3....0....1....3....4....4....0....2....2....1....2....1
..3....3....2....4....0....3....2....3....3....3....4....2....0....0....4....0
..1....1....1....1....1....3....4....3....0....1....3....2....2....1....0....1
..3....0....2....1....4....4....4....4....0....1....3....1....0....3....2....4
..4....0....1....3....0....1....2....1....1....3....2....3....1....4....2....0
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CROSSREFS
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KEYWORD
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AUTHOR
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STATUS
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approved
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