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A152223
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a(n) = -4*a(n-1) + 6*a(n-2), n>1; a(0)=1, a(1)=-6.
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4
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1, -6, 30, -156, 804, -4152, 21432, -110640, 571152, -2948448, 15220704, -78573504, 405618240, -2093913984, 10809365376, -55800945408, 288059973888, -1487045568000, 7676542115328, -39628441869312, 204573020169216, -1056062731892736, 5451689048586240
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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LINKS
| Reinhard Zumkeller, Table of n, a(n) for n = 0..1000
Index to sequences with linear recurrences with constant coefficients, signature (-4,6).
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FORMULA
| G.f.: (1-2x)/(1+4x-6x^2). a(n) = Sum_{k, 0<=k<=n}A147703(n,k)*(-7)^k .
a(n) = (1/2)*((-2-sqrt(10))^n+(-2+sqrt(10))^n)+(1/5)*sqrt(10)*((-2-sqrt(10))^n-(-2+sqrt(10))^n). [From Bruno Berselli, Jan 12 2012]
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MATHEMATICA
| LinearRecurrence[{-4, 6}, {1, -6}, 23] (* Bruno Berselli, Jan 12 2012 *)
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PROG
| (PARI) Vec((1-2*x)/(1+4*x-6*x^2)+O(x^99)) \\ Charles R Greathouse IV, Jan 12 2012
(Haskell)
a152223 n = a152223_list !! n
a152223_list = 1 : -6 : zipWith (-)
(map (* 6) $ a152223_list) (map (* 4) $ tail a152223_list)
-- Reinhard Zumkeller, Jan 12 2012
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CROSSREFS
| Sequence in context: A126474 A127017 A152224 * A026112 A038155 A026331
Adjacent sequences: A152220 A152221 A152222 * A152224 A152225 A152226
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KEYWORD
| sign,easy
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AUTHOR
| Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Nov 29 2008
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EXTENSIONS
| a(17)-a(23) corrected by Charles R Greathouse IV, Jan 12 2012
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