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A213788 a(n) = Sum_{1<=i<j<k<=n} (P(i)*P(j)*P(k), where P(m) is the k-th Pell number A000129(m). 2
0, 0, 0, 10, 214, 3491, 52001, 748788, 10636260, 150248190, 2117562834, 29816257390, 419662506490, 5905775317025, 83104503504515, 1169392060102440, 16454728773220584, 231536384221100316, 3257968708458764196, 45843125116860034258, 645061876629223784830, 9076710308820189950975 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..275

Index entries for linear recurrences with constant coefficients, signature (21,-98,-34,616,-532,-62,98,-7,-1).

FORMULA

G.f.: (x^4+2*x^3-23*x^2+4*x+10)*x^3 / ((x-1) * (x^2+14*x-1) * (x^2-2*x-1) * (x^2+2*x-1) * (x^2-6*x+1)). - Alois P. Heinz, Jun 20 2012

MAPLE

a:= n-> (Matrix(9, (i, j)-> `if`(i=j-1, 1, `if`(i=9,

         [-1, -7, 98, -62, -532, 616, -34, -98, 21][j], 0)))^(n+3).

         <<5, -1, 0, 0, 0, 0, 10, 214, 3491>>)[1, 1]:

seq (a(n), n=0..30);  # Alois P. Heinz, Jun 20 2012

MATHEMATICA

LinearRecurrence[{21, -98, -34, 616, -532, -62, 98, -7, -1}, {0, 0, 0, 10, 214, 3491, 52001, 748788, 10636260}, 30] (* Jean-Fran├žois Alcover, Feb 17 2016 *)

PROG

(PARI) concat(vector(3), Vec((x^4+2*x^3-23*x^2+4*x+10)*x^3 / ((x-1) * (x^2+14*x-1) * (x^2-2*x-1) * (x^2+2*x-1) * (x^2-6*x+1)) + O(x^30))) \\ Colin Barker, Feb 17 2016

CROSSREFS

Cf. A000129, A213785.

Sequence in context: A245981 A245985 A211912 * A278125 A274763 A002967

Adjacent sequences:  A213785 A213786 A213787 * A213789 A213790 A213791

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane, Jun 20 2012

STATUS

approved

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Last modified June 24 18:25 EDT 2019. Contains 324330 sequences. (Running on oeis4.)