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A087281 Lucas numbers L(7n). +0
1
2, 29, 843, 24476, 710647, 20633239, 599074578, 17393796001, 505019158607, 14662949395604, 425730551631123, 12360848946698171, 358890350005878082, 10420180999117162549, 302544139324403592003, 8784200221406821330636 (list; graph; listen)
OFFSET

0,1

COMMENT

a(n+1)/a(n) converges to (29+sqrt(845))/2 = 29.0344418537... a(0)/a(1)=2/29; a(1)/a(2)=29/843; a(2)/a(3)=843/24476; a(3)/a(4)=24476/710647; ... etc. Lim a(n)/a(n+1) as n approaches infinity = 0.0344418537... = 2/(29+sqrt(845)) = (sqrt(845)-29)/2.

LINKS

Tanya Khovanova, Recursive Sequences

Index entries for recurrences a(n) = k*a(n - 1) +/- a(n - 2)

FORMULA

a(n) =29a(n-1) + a(n-2), starting with a(0) = 2 and a(1) = 29, a(n) = ((29+sqrt(845))/2)^n + ((29-sqrt(845))/2)^n, (a(n))^2 =a(2n)-2 if n=1, 3, 5..., (a(n))^2 =a(2n)+2 if n=2, 4, 6....

G.f.: (2-29*x)/(1-29*x-x^2). [From Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Nov 02 2008]

EXAMPLE

a(4) = 710647 = 29a(3) + a(2) = 29*24476+ 843=((29+sqrt(845))/2)^4 + ( (29-sqrt(845))/2)^4 =710646.9999985928 + 0.0000014071 = 710647.

CROSSREFS

Cf. A000032.

Sequence in context: A013517 A006988 A090251 this_sequence A024234 A077282 A059725

Adjacent sequences: A087278 A087279 A087280 this_sequence A087282 A087283 A087284

KEYWORD

easy,nonn

AUTHOR

Nikolay V. Kosinov (kosinov(AT)unitron.com.ua), Oct 19 2003

EXTENSIONS

More terms from Ray Chandler (rayjchandler(AT)sbcglobal.net), Feb 14 2004

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Last modified December 20 00:58 EST 2009. Contains 171054 sequences.


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