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Search: id:A006043
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| A006043 |
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A traffic light problem: expansion of 2/(1-3x)^3.
(Formerly M2107)
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+0
6
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| 2, 18, 108, 540, 2430, 10206, 40824, 157464, 590490, 2165130, 7794468, 27634932, 96722262, 334807830, 1147912560, 3902902704, 13172296626, 44165935746, 147219785820, 488149816140, 1610894393262, 5292938720718
(list; graph; listen)
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OFFSET
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0,1
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COMMENT
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Column 2 of square array A152818. [From Omar E. Pol (info(AT)polprimos.com), Jan 05 2009]
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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).
F. A. Haight, Overflow at a traffic light, Biometrika, 46 (1959), 420-424.
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FORMULA
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a(n)=n*(n-1)*3^(n-2), n>=2 . - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Apr 25 2007
a(n) = 3^n*(n+2)!/n!. [From Omar E. Pol (info(AT)polprimos.com), Jan 05 2009]
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MAPLE
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seq(n*(n-1)*3^(n-2), n=2..23); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Apr 25 2007
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CROSSREFS
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Cf. A006044, A000142, A152818, A154120. [From Omar E. Pol (info(AT)polprimos.com), Jan 05 2009]
Sequence in context: A005969 A094251 A101570 this_sequence A112328 A038721 A064837
Adjacent sequences: A006040 A006041 A006042 this_sequence A006044 A006045 A006046
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KEYWORD
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nonn,easy
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), Simon Plouffe (simon.plouffe(AT)gmail.com)
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