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A081015
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Lucas(4n+3)+1, or 5*Fibonacci(2n+1)*Fibonacci(2n+2).
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1
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5, 30, 200, 1365, 9350, 64080, 439205, 3010350, 20633240, 141422325, 969323030, 6643838880, 45537549125, 312119004990, 2139295485800, 14662949395605, 100501350283430, 688846502588400, 4721424167835365, 32361122672259150
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,1
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REFERENCES
| Hugh C. Williams, Edouard Lucas and Primality Testing, John Wiley and Sons, 1998, p. 75
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FORMULA
| a(n) = 8a(n-1)-8a(n-2)+a(n-3)
a(n)=1+2*{[(7/2)-(3/2)*sqrt(5)]^n+[(7/2)+(3/2)*sqrt(5)]^n}+sqrt(5)*{[(7/2)+(3/2)*sqrt(5)]^n-[(7/2)-(3/2)*sqrt(5)]^n}, with n>=0 [From Paolo P. Lava (paoloplava(AT)gmail.com), Dec 01 2008]
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MAPLE
| luc := proc(n) option remember: if n=0 then RETURN(2) fi: if n=1 then RETURN(1) fi: luc(n-1)+luc(n-2): end: for n from 0 to 25 do printf(`%d, `, luc(4*n+3)+1) od:
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MATHEMATICA
| Join[{a=1, b=6}, Table[c=7*b-1*a-1; a=b; b=c, {n, 60}]]*5 (*From Vladimir Joseph Stephan Orlovsky, Jan 18 2011*)
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CROSSREFS
| Cf. A000045 (Fibonacci numbers), A000032 (Lucas numbers).
Sequence in context: A196471 A034164 A103433 * A090139 A107265 A196678
Adjacent sequences: A081012 A081013 A081014 * A081016 A081017 A081018
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KEYWORD
| nonn,easy
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AUTHOR
| R. K. Guy (rkg(AT)cpsc.ucalgary.ca), Mar 01, 2003
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EXTENSIONS
| More terms and Maple code from James A. Sellers (sellersj(AT)math.psu.edu), Mar 03, 2003
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