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A049870
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a(n)=Sum{a(k): k=0,1,2,...,n-4,n-2,n-1}; a(n-3) is not a summand; 3 initial terms required.
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0
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1, 2, 4, 6, 11, 20, 38, 71, 133, 248, 463, 864, 1613, 3011, 5621, 10493, 19588, 36566, 68260, 127425, 237872, 444050, 828935, 1547423, 2888668, 5392451, 10066414, 18791583, 35079383, 65484803, 122244437, 228201074, 425996728
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OFFSET
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0,2
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LINKS
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FORMULA
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a(n)=2*a(n-1)-a(n-3)+a(n-4); 4 initial terms required.
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MATHEMATICA
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LinearRecurrence[{2, 0, -1, 1}, {1, 2, 4, 6}, 40] (* Harvey P. Dale, Mar 23 2015 *)
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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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