OFFSET
0,2
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (8,-28,56,-70,56,-28,8,-1).
FORMULA
From Colin Barker, Jul 29 2019: (Start)
G.f.: 2*x*(13 + 15*x) / (1 - x)^8.
a(n) = (n*(1080 + 2946*n + 3121*n^2 + 1665*n^3 + 475*n^4 + 69*n^5 + 4*n^6)) / 360.
a(n) = 8*a(n-1) - 28*a(n-2) + 56*a(n-3) - 70*a(n-4) + 56*a(n-5) - 28*a(n-6) + 8*a(n-7) - a(n-8) for n>7.
(End)
MATHEMATICA
LinearRecurrence[{8, -28, 56, -70, 56, -28, 8, -1}, {0, 26, 238, 1176, 4200, 12180, 30492, 68376}, 40] (* or *) a = 1/360 (1080 #1 + 2946 #1^2 + 3121 #1^3 + 1665 #1^4 + 475 #1^5 + 69 #1^6 + 4 #1^7) &; Table[a[n], {n, 0, 40}]
Table[(8*n + 18)*Pochhammer[n, 6]/6!, {n, 0, 50}] (* G. C. Greubel, Oct 23 2017 *)
PROG
(PARI) for(n=0, 50, print1((8*n + 18)*(n+5)*(n+4)*(n+3)*(n+2)*(n+1)*n/6!, ", ")) \\ G. C. Greubel, Oct 23 2017
(PARI) concat(0, Vec(2*x*(13 + 15*x) / (1 - x)^8 + O(x^40))) \\ Colin Barker, Jul 29 2019
(Magma) [(8*n + 18)*(n+5)*(n+4)*(n+3)*(n+2)*(n+1)*n/Factorial(6): n in [0..50]]; // G. C. Greubel, Oct 23 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Peter Luschny, Oct 13 2017
STATUS
approved