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A081019
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Lucas(4n+3)-1, or Lucas(2n+1)*Lucas(2n+2).
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0
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3, 28, 198, 1363, 9348, 64078, 439203, 3010348, 20633238, 141422323, 969323028, 6643838878, 45537549123, 312119004988, 2139295485798, 14662949395603, 100501350283428, 688846502588398, 4721424167835363, 32361122672259148
(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
| with(combinat): 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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CROSSREFS
| Cf. A000045 (Fibonacci numbers), A000032 (Lucas numbers).
Sequence in context: A012778 A074922 A160872 * A091120 A045737 A003466
Adjacent sequences: A081016 A081017 A081018 * A081020 A081021 A081022
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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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