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A113726
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A Jacobsthal convolution.
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2
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1, 0, 1, 4, 5, 8, 25, 44, 77, 176, 353, 660, 1365, 2776, 5417, 10876, 21981, 43648, 87153, 175076, 349669, 698280, 1398585, 2797260, 5590381, 11184720, 22373761, 44735284, 89474165, 178969208, 357910345, 715807004, 1431683837, 2863325216
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OFFSET
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0,4
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COMMENTS
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LINKS
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FORMULA
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G.f.: 1/((1-x-2*x^2)*(1+x+2*x^2)).
a(n) = a(n-2) + 4*a(n-3) + 4*a(n-4).
a(n) = sum{k=0..floor(n/2), C(n-k, k)*2^k*(1+(-1)^(n-k))/2}.
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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