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A140322
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-1/6 +(-1)^n/2 +2*4^n/3.
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2
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1, 2, 11, 42, 171, 682, 2731, 10922, 43691, 174762, 699051, 2796202, 11184811, 44739242, 178956971, 715827882, 2863311531, 11453246122, 45812984491, 183251937962, 733007751851, 2932031007402, 11728124029611, 46912496118442, 187649984473771, 750599937895082
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| a(n+1)-4a(n)= period 2: repeat -2, 3.
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LINKS
| Vincenzo Librandi, Table of n, a(n) for n = 0..1000
Index to sequences with linear recurrences with constant coefficients, signature (4,1,-4)
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FORMULA
| a(n)=4a(n-1)+a(n-2)-4a(n-3).
G.f. ( 1-2*x+2*x^2 ) / ( (x-1)*(4*x-1)*(1+x) ). - R. J. Mathar, Nov 21 2011
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PROG
| (MAGMA) [-1/6+(1/2)*(-1)^n+(2/3)*4^n: n in [0..25]]; // Vincenzo Librandi, Aug 09 2011
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CROSSREFS
| Sequence in context: A160945 A079808 A089658 * A027247 A128241 A141190
Adjacent sequences: A140319 A140320 A140321 * A140323 A140324 A140325
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KEYWORD
| nonn,easy
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AUTHOR
| Paul Curtz (bpcrtz(AT)free.fr), May 26 2008
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