A137788 a(n) = 6^n - 5^n - 4^n - 3^n - 2^n.

-8, -18, -8, 318, 3352, 26142, 183112, 1216638, 7842232, 49591902, 309595432, 1915328958, 11771279512, 71987413662, 438579282952, 2664183937278, 16146410851192, 97676152243422, 590010212989672, 3559688008961598, 21455704973213272, 129219894479953182, 777738831202779592

Offset

1,1

Links

G. C. Greubel, Table of n, a(n) for n = 1..1000

Index entries for linear recurrences with constant coefficients, signature (20,-155,580,-1044,720).

Formula

From R. J. Mathar, Jun 15 2009: (Start)

G.f.: 2*x*(4 - 71*x + 444*x^2 - 1164*x^3 + 1080*x^4)/((6*x-1)*(4*x-1)*(3*x-1)*(2*x-1)*(5*x-1)).

a(n) = 20*a(n-1) - 155*a(n-2) + 580*a(n-3) - 1044*a(n-4) + 720*a(n-5). (End)

Example

- 8*x - 18*x^2 - 8*x^3 + 318*x^4 + 3352*x^5 + 26142*x^6 + 183112*x^7 + ...

Maple

a:=proc (n) options operator, arrow: 6^n-5^n-4^n-3^n-2^n end proc: seq(a(n), n =1..20); # Emeric Deutsch, May 25 2008

Mathematica

Array[6^#-5^#-4^#-3^#-2^# &, 10]
LinearRecurrence[{20, -155, 580, -1044, 720}, {-8, -18, -8, 318, 3352}, 30] (* Harvey P. Dale, Jan 23 2012 *)

Prog

(PARI) {a(n) = 6^n - 5^n - 4^n - 3^n - 2^n} /* Michael Somos, Jan 06 2012 */

Crossrefs

Sequence in context: A107779 A018874 A163900 * A378228 A333828 A133202

Adjacent sequences: A137785 A137786 A137787 * A137789 A137790 A137791

Keyword

sign,easy

Author

Vladimir Joseph Stephan Orlovsky, Apr 28 2008

Extensions

More terms from Alexander R. Povolotsky and Emeric Deutsch, May 01 2008

Status

approved