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A017817
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a(0)=1, a(1)=a(2)=0, a(3)=1; a(n)=a(n-3)+a(n-4).
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12
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1, 0, 0, 1, 1, 0, 1, 2, 1, 1, 3, 3, 2, 4, 6, 5, 6, 10, 11, 11, 16, 21, 22, 27, 37, 43, 49, 64, 80, 92, 113, 144, 172, 205, 257, 316, 377, 462, 573, 693, 839, 1035, 1266, 1532, 1874, 2301, 2798, 3406, 4175, 5099, 6204, 7581, 9274, 11303, 13785, 16855, 20577, 25088
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,8
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LINKS
| Index entries for two-way infinite sequences
INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 484
E. Wilson, The Scales of Mt. Meru
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FORMULA
| G.f.: 1/(1-x^3-x^4).
a(n)/a(n-1) tends to r = 1.2207440846..., a real root of x^4 - x - 1 = 0. - Gary W. Adamson (qntmpkt(AT)yahoo.com), Oct 22 2006
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MATHEMATICA
| a=b=c=0; d=1; lst={d}; Do[AppendTo[lst, e=a+b]; a=b; b=c; c=d; d=e, {n, 0, 5!}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), May 28 2010]
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PROG
| (PARI) a(n)=polcoeff(if(n<0, (1+x)/(1+x-x^4), 1/(1-x^3-x^4))+x*O(x^abs(n)), abs(n))
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CROSSREFS
| A003269(n)=a(-4-n)(-1)^n.
Sequence in context: A131336 A052253 A127838 * A189913 A053268 A101417
Adjacent sequences: A017814 A017815 A017816 * A017818 A017819 A017820
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
| More terms from Klaus Strassburger (strass(AT)ddfi.uni-duesseldorf.de), Dec 17 1999
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