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Search: id:A005120
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| A005120 |
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a(n+6) = -3a(n+5)-5a(n+4)-5a(n+3)-5a(n+2)-3a(n+1)-a(n).
(Formerly M3770)
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+0
1
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| 0, 1, -1, 1, -1, -1, 5, -8, 7, 1, -19, 43, -55, 27, 64, -211, 343, -307, -85, 911, -1919, 2344, -989, -3151, 9625, -15049, 12609, 5671, -42496, 85609, -100225, 33977, 154007, -437009, 657901, -513512, -335665, 1974097, -3808891, 4265379
(list; graph; listen)
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OFFSET
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0,7
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COMMENT
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This is a divisibility sequence. If d divides n then a(d) divides a(n).
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
M. Duboue, Une suite recurrente remarquable, Europ. J. Combin., 4 (1983), 205-214.
H. C. Williams, Edouard Lucas and Primality Testing, Wiley, 1998, p. 455. Math. Rev. 2000b:11139
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FORMULA
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G.f.: x(1+2x+3x^2+2x^3+x^4)/(1+3x+5x^2+5x^3+5x^4+3x^5+x^6).
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PROGRAM
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(PARI) a(n)=polcoeff(x*(1+2*(x+x^3)+3*x^2+x^4)/(1+3*(x+x^5)+5*(x^2+x^3+x^4)+x^6)+x*O(x^\ n), n)
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CROSSREFS
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Cf. A001608.
Sequence in context: A160043 A145432 A070371 this_sequence A133731 A021067 A047914
Adjacent sequences: A005117 A005118 A005119 this_sequence A005121 A005122 A005123
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KEYWORD
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sign,easy
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
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Edited by Michael Somos, Aug 02, 2002
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