A164609 a(n) = 10*a(n-1) - 17*a(n-2) for n > 1; a(0) = 1, a(1) = 13.
1, 13, 113, 909, 7169, 56237, 440497, 3448941, 27000961, 211377613, 1654759793, 12954178509, 101410868609, 793887651437, 6214891748017, 48652827405741, 380875114341121, 2981653077513613, 23341653831337073, 182728435995639309
Offset: 0
Links
- G. C. Greubel, Table of n, a(n) for n = 0..1000 (terms 0..144 from Vincenzo Librandi)
- Index entries for linear recurrences with constant coefficients, signature (10, -17).
Programs
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Magma
Z
:=PolynomialRing(Integers()); N :=NumberField(x^2-2); S:=[ ((2+4*r)*(5+2*r)^n+(2-4*r)*(5-2*r)^n)/4: n in [0..19] ]; [ Integers()!S[j]: j in [1..#S] ]; // Klaus Brockhaus, Aug 22 2009 -
Mathematica
LinearRecurrence[{10,-17},{1,13},20] (* Harvey P. Dale, Nov 05 2014 *)
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PARI
x='x+O('x^50); Vec((1+3*x)/(1-10*x+17*x^2)) \\ G. C. Greubel, Aug 10 2017
Formula
a(n) = 10*a(n-1) - 17*a(n-2) for n > 1; a(0) = 1, a(1) = 13.
a(n) = ((2+4*sqrt(2))*(5+2*sqrt(2))^n + (2-4*sqrt(2))*(5-2*sqrt(2))^n)/4.
G.f.: (1+3*x)/(1-10*x+17*x^2).
E.g.f.: exp(5*x)*(cosh(2*sqrt(2)*x) + 2*sqrt(2)*sinh(2*sqrt(2)*x)). - G. C. Greubel, Aug 10 2017
Extensions
Edited and extended beyond a(5) by Klaus Brockhaus, Aug 22 2009
Comments