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A084241
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a(n)=-5a(n-1)-4a(n-2), a(0)=0,a(1)=1.
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2
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0, 1, -5, 21, -85, 341, -1365, 5461, -21845, 87381, -349525, 1398101, -5592405, 22369621, -89478485, 357913941, -1431655765, 5726623061, -22906492245, 91625968981, -366503875925, 1466015503701, -5864062014805, 23456248059221, -93824992236885
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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COMMENTS
| abs(a(n))=A002450(n)=A001045(2n). Binomial transform is (0,1,-3,9,-27,...).
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FORMULA
| a(n)=((-1)^n-(-4)^n)/3; a(n)=sum{k=1..n, (-1)^(n+k)binomial(n, k)(-3)^(k-1) }; G.f.: x/((1+x)(1+4x)); E.g.f.: (exp(-x)-exp(-4x))/3.
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CROSSREFS
| Apart from signs, identical to A002450. Cf. A084240.
Sequence in context: A002054 A028948 A002450 * A187063 A026855 A097113
Adjacent sequences: A084238 A084239 A084240 * A084242 A084243 A084244
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KEYWORD
| easy,sign
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AUTHOR
| Paul Barry (pbarry(AT)wit.ie), May 21 2003
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