This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A081077 Lucas(4n+2)+3, or Lucas(2n)*Lucas(2n+2). 0
 6, 21, 126, 846, 5781, 39606, 271446, 1860501, 12752046, 87403806, 599074581, 4106118246, 28143753126, 192900153621, 1322157322206, 9062201101806, 62113250390421, 425730551631126, 2918000611027446, 20000273725560981 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 REFERENCES Hugh C. Williams, Edouard Lucas and Primality Testing, John Wiley and Sons, 1998, p. 75 LINKS FORMULA a(n) = 8a(n-1)-8a(n-2)+a(n-3) a(n)=A081067(n)+1. - R. J. Mathar, May 18 2007 G.f.: -3*(2-9*x+2*x^2)/(x-1)/(x^2-7*x+1) = -3/(x-1)+(-3*x+3)/(x^2-7*x+1). - R. J. Mathar, Nov 18 2007 a(n)=3+(3/2)*{[(7/2)-(3/2)*sqrt(5)]^n+[(7/2)+(3/2)*sqrt(5)]^n}+(1/2)*sqrt(5)*{[(7/2)+(3/2) *sqrt(5)]^n-[(7/2)-(3/2)*sqrt(5)]^n}, with n>=0 [From Paolo P. Lava, Dec 01 2008] 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 40 do printf(`%d, `, luc(4*n+2)+3) od: CROSSREFS Cf. A000032 (Lucas numbers). Cf. A081067. Sequence in context: A012840 A013320 A056308 * A093775 A058821 A054366 Adjacent sequences:  A081074 A081075 A081076 * A081078 A081079 A081080 KEYWORD nonn,easy AUTHOR R. K. Guy, Mar 04, 2003 EXTENSIONS More terms and Maple code from James A. Sellers, Mar 05, 2003 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Transforms | Puzzles | Hot | Classics
Recent Additions | More pages | Superseeker | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement .