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Search: id:A115102
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| A115102 |
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a(0)=2, a(1)=8, a(n)=a(n-1)+2a(n-2). |
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+0
1
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| 2, 8, 12, 28, 52, 108, 212, 428, 852, 1708, 3412, 6828, 13652, 27308, 54612, 109228, 218452, 436908, 873812, 1747628, 3495252, 6990508, 13981012, 27962028, 55924052, 111848108
(list; graph; listen)
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OFFSET
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0,1
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FORMULA
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a(n)=-(1/3)*[4*(-1)^n+10*2^n], with n>=0 [From Paolo P. Lava (ppl(AT)spl.at), Aug 05 2008]
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MATHEMATICA
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M = {{0, 1, -1}, {-1, 0, 1}, {1, -1, 0}}; o[M_] = IdentityMatrix[3]*Flatten[Table[Table[If[n - m == 0, {}, M[[n, m]]^2 + M[[m, n]]^2], {n, 1, m}], {m, 1, 3}]]; M1 = M.M + o[M]; w[0] = {2, 3, 5}; w[n_] := w[n] = M1.w[n - 1] a0 = Table[w[n][[1]], {n, 0, 25}]
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CROSSREFS
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Cf. A078008, A014551, A001045.
Sequence in context: A135957 A107755 A027718 this_sequence A047174 A048074 A126775
Adjacent sequences: A115099 A115100 A115101 this_sequence A115103 A115104 A115105
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KEYWORD
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nonn
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AUTHOR
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Roger Bagula (rlbagulatftn(AT)yahoo.com), Mar 02 2006
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EXTENSIONS
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Edited by njas, Dec 04 2006
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