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A078026
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Expansion of (1-x)/(1-x^2-2*x^3).
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0
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1, -1, 1, 1, -1, 3, 1, 1, 7, 3, 9, 17, 15, 35, 49, 65, 119, 163, 249, 401, 575, 899, 1377, 2049, 3175, 4803, 7273, 11153, 16879, 25699, 39185, 59457, 90583, 137827, 209497, 318993, 485151, 737987, 1123137, 1708289, 2599111, 3954563, 6015689, 9152785, 13924815
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,6
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FORMULA
| a(n)=sum(m=1..n, sum(i=0..n-m, binomial(m+i-1,m-1)*sum(j=0..m, binomial(j,n-3*m+2*j-i)*2^(m-j)*binomial(m,j)*(-1)^(-n+3*m-j+i)))); [From Vladimir Kruchinin kru(AT)ie.tusur.ru, May 12 2011]
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PROG
| (Maxima)
a(n):=sum(sum(binomial(m+i-1, m-1)*sum(binomial(j, n-3*m+2*j-i)*2^(m-j)*binomial(m, j)*(-1)^(-n+3*m-j+i), j, 0, m), i, 0, n-m), m, 1, n); [From Vladimir Kruchinin kru(AT)ie.tusur.ru, May 12 2011]
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CROSSREFS
| Sequence in context: A071812 A116407 A135288 * A126713 A140068 A179745
Adjacent sequences: A078023 A078024 A078025 * A078027 A078028 A078029
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KEYWORD
| sign
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Nov 17 2002
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