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A202120
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Number of -4..4 arrays of n elements with first, second and third differences also in -4..4
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1
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9, 61, 323, 1279, 5205, 21093, 85771, 348841, 1418711, 5769945, 23467095, 95443593, 388180467, 1578775913, 6421070989, 26115267153, 106213924727, 431984776463, 1756933935339, 7145661191995, 29062261695493, 118199706395781
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OFFSET
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1,1
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COMMENTS
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LINKS
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FORMULA
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Empirical: a(n) = 5*a(n-1) -3*a(n-2) -2*a(n-3) -30*a(n-5) +38*a(n-6) +3*a(n-7) +7*a(n-8) +53*a(n-9) -231*a(n-10) +162*a(n-11) +158*a(n-12) -324*a(n-13) +637*a(n-14) -176*a(n-15) -712*a(n-16) +106*a(n-17) -545*a(n-18) +1800*a(n-19) +1339*a(n-20) -2116*a(n-21) -1941*a(n-22) -4947*a(n-23) +1650*a(n-24) +8446*a(n-25) +2274*a(n-26) +2636*a(n-27) -8685*a(n-28) -8752*a(n-29) +6866*a(n-30) +5310*a(n-31) +13318*a(n-32) +342*a(n-33) -14687*a(n-34) -7785*a(n-35) -16694*a(n-36) -688*a(n-37) +10880*a(n-38) +8362*a(n-39) +17910*a(n-40) +1396*a(n-41) -5792*a(n-42) -4461*a(n-43) -9176*a(n-44) +954*a(n-45) +957*a(n-46) -1163*a(n-47) +2833*a(n-48) +949*a(n-49) +1131*a(n-50) +266*a(n-51) -1730*a(n-52) -345*a(n-53) +290*a(n-54) -5*a(n-55) -200*a(n-56) -141*a(n-57) +140*a(n-58) +85*a(n-59) +14*a(n-60) +18*a(n-61) -a(n-62) -2*a(n-63) for n>72
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EXAMPLE
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Some solutions for n=7
..2....1...-4....0....4....0....3....3....4...-1...-2....2...-1...-4....1....1
.-2....1...-3...-2....4...-2....0...-1....0....2...-3....0...-2...-3...-3....4
.-4....2...-3...-3....4...-2....0...-4...-2....4...-3...-3...-4....1...-4....3
.-2....1...-4...-1....3...-1....2...-3...-3....3...-4...-3...-4....4...-3....1
..1....0...-4....2....4....0....2...-2...-3....2...-3...-4...-2....3...-2....1
..2...-1...-3....3....4....0....4....0...-1....0...-3...-3...-1....2...-2....1
..3...-3...-3....0....2...-4....4....0....0...-1...-2...-4...-1....3....0....1
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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