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A147688
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((6+sqrt8)^n+(6-sqrt8)^n))/2
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0
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1, 6, 44, 360, 3088, 26976, 237248, 2091648, 18456832, 162915840, 1438198784, 12696741888, 112091336704, 989587267584, 8736489783296, 77129433907200, 680931492954112, 6011553766047744, 53072563389857792, 468547255228956672
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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FORMULA
| a(n)=12*a(n-1)-28*a(n-2), a(0)=1, a(1)=6 . G.f.:(1-6x)/(1-12x+28x^2). a(n)=(Sum_{k, 0<=k<=n}A098158(n,k)*6^(2k)*8^(n-k))/6^n. [From Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Nov 13 2008]
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EXAMPLE
| a(3)=360
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MATHEMATICA
| LinearRecurrence[{12, -28}, {1, 6}, 30] (* From Harvey P. Dale, Apr 23 2011 *)
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PROG
| (MAGMA) Z<x>:= PolynomialRing(Integers()); N<r8>:=NumberField(x^2-8); S:=[ ((6+r8)^n+(6-r8)^n)/2: n in [0..19] ]; [ Integers()!S[j]: j in [1..#S] ]; [From Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Nov 13 2008]
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CROSSREFS
| Sequence in context: A108452 A005591 A052204 * A090442 A084965 A203159
Adjacent sequences: A147685 A147686 A147687 * A147689 A147690 A147691
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KEYWORD
| nonn,easy
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AUTHOR
| Al Hakanson (hawkuu(AT)gmail.com), Nov 10 2008
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EXTENSIONS
| Extended beyond a(6) by Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Nov 13 2008
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