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Search: id:A121470
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| A121470 |
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Let M = [{0, 1}, {-1, 2}]; v[1] = {1, 7}; w[n] = {0, 3} if n is even, otherwise {0, 6}. Let v[n] = M.v[n - 1] + w[n]; then a(n) = v[n][[1]]. |
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2
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| 1, 7, 16, 31, 49, 73, 100, 133, 169, 211, 256, 307, 361, 421, 484, 553, 625, 703, 784, 871, 961, 1057, 1156, 1261, 1369, 1483, 1600, 1723, 1849, 1981, 2116, 2257, 2401, 2551, 2704, 2863, 3025, 3193, 3364, 3541, 3721, 3907, 4096, 4291, 4489, 4693, 4900
(list; graph; listen)
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OFFSET
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1,2
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MAPLE
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A121410 := proc(nmin) local M, a, v, wev, wod, n ; a := [] ; M := linalg[matrix](2, 2, [0, 1, -1, 2]) ; v := linalg[vector](2, [1, 7]) ; wev := linalg[vector](2, [0, 3]) ; wod := linalg[vector](2, [0, 6]) ; while nops(a) < nmin do a := [op(a), v[1]] ; n := nops(a)+1 ; v := evalm(M &* v) ; if n mod 2 = 0 then v := evalm(v+wev) ; else v := evalm(v+wod) ; fi ; od: RETURN(a) ; end: A121410(80) ; - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Sep 18 2007
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MATHEMATICA
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M := {{0, 1}, {-1, 2} } v[1] = {1, 7} w[n_] = If[Mod[n, 2] == 0, {0, 3}, {0, 6}] v[n_] := v[n] = M.v[n - 1] + w[n] a = Table[v[n][[1]], {n, 1, 30}]
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CROSSREFS
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Cf. A003215, A005448.
Sequence in context: A133694 A024627 A140511 this_sequence A019541 A036834 A020941
Adjacent sequences: A121467 A121468 A121469 this_sequence A121471 A121472 A121473
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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), Sep 07 2006
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EXTENSIONS
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Edited by njas, Sep 16 2006
More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Sep 18 2007
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