Location via proxy:   [ UP ]  
[Report a bug]   [Manage cookies]                
A098245
Chebyshev polynomials S(n,227).
5
1, 227, 51528, 11696629, 2655083255, 602692202256, 136808474828857, 31054921093948283, 7049330279851431384, 1600166918605180975885, 363230841193096230094511, 82451800783914239050478112
OFFSET
0,2
COMMENTS
Used for all positive integer solutions of Pell equation x^2 - 229*y^2 = -4. See A098246 with A098247.
FORMULA
a(n) = S(n, 227) = U(n, 227/2) = S(2*n+1, sqrt(229))/sqrt(229) with S(n, x) = U(n, x/2) Chebyshev's polynomials of the second kind, A049310. S(-1, x) = 0 = U(-1, x).
a(n) = 227*a(n-1)-a(n-2), n >= 1; a(0)=1, a(1)=227; a(-1):=0.
a(n) = (ap^(n+1) - am^(n+1))/(ap-am) with ap := (227+15*sqrt(229))/2 and am := (227-15*sqrt(229))/2 = 1/ap.
G.f.: 1/(1-227*x+x^2).
MATHEMATICA
CoefficientList[Series[1/(1 - 227*x + x^2), {x, 0, 15}], x] (* Wesley Ivan Hurt, Feb 09 2017 *)
LinearRecurrence[{227, -1}, {1, 227}, 20] (* Harvey P. Dale, Jan 15 2019 *)
CROSSREFS
Sequence in context: A115998 A092324 A122976 * A343169 A190027 A090943
KEYWORD
nonn,easy
AUTHOR
Wolfdieter Lang, Sep 10 2004
STATUS
approved