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Search: id:A146965
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| A146965 |
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((5+sqrt7)^n+(5-sqrt7)^n)/2 |
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+0
2
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| 1, 5, 32, 230, 1724, 13100, 99968, 763880, 5839376, 44643920, 341330432, 2609713760, 19953189824, 152557050560, 1166413088768, 8918103977600, 68185604178176, 521330170184960, 3985960826642432, 30475665203095040
(list; graph; listen)
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OFFSET
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0,2
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FORMULA
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a(n)=10*a(n-1)-18*a(n-2); a(0)=1, a(1)=5. G.f.: (1-5*x)/(1-10*x+18*x^2). [From Philippe DELEHAM (kolotoko(AT)wanadoo.fr) and Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Nov 05 2008]
a(n)=(Sum_{k, 0<=k<=n}A098158(n,k)*5^(2*k)*7^(n-k)}/5^n. [From Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Nov 06 2008]
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EXAMPLE
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a(3)=230
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PROGRAM
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(MAGMA) Z<x>:= PolynomialRing(Integers()); N<r7>:=NumberField(x^2-7); S:=[ ((5+r7)^n+(5-r7)^n)/2: n in [0..19] ]; [ Integers()!S[j]: j in [1..#S] ]; [From Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Nov 05 2008]
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CROSSREFS
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Sequence in context: A164594 A065071 A153396 this_sequence A053157 A102231 A127089
Adjacent sequences: A146962 A146963 A146964 this_sequence A146966 A146967 A146968
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KEYWORD
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nonn
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AUTHOR
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Al Hakanson (hawkuu(AT)gmail.com), Nov 03 2008
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EXTENSIONS
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Extended beyond a(7) by Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Nov 05 2008
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