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A154023
a(n+2) = 36*a(n+1) - a(n), a(1)=0, a(2)=6.
1
0, 6, 216, 7770, 279504, 10054374, 361677960, 13010352186, 468011000736, 16835385674310, 605605873274424, 21784976052204954, 783653532006103920, 28189742176167536166, 1014047064810025198056, 36477504590984739593850
OFFSET
1,2
COMMENTS
If a(n)=x and a(n+1)=y then (x^2+y^2)/(xy+1)=36.
FORMULA
From R. J. Mathar, Oct 18 2010: (Start)
a(n)= +36*a(n-1) -a(n-2)
a(n) = 6*A144128(n-1).
G.f.: 6*x/(1 -36*x +x^2). (End)
MATHEMATICA
LinearRecurrence[{36, -1}, {0, 6}, 50] (* Vincenzo Librandi, Jan 30 2012 *)
PROG
(PARI) concat(0, Vec(6/(1-36*x+x^2)+O(x^98))) \\ Charles R Greathouse IV, Dec 27 2011
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Jan 04 2009
EXTENSIONS
Edited by N. J. A. Sloane, Jun 23 2010 at the suggestion of Joerg Arndt.
Missing digit inserted in a(8) by R. J. Mathar, Oct 18 2010
STATUS
approved