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 (7,-21,35,-35,21,-7,1).
FORMULA
From Colin Barker, Jul 28 2019: (Start)
G.f.: x*(11 + 14*x) / (1 - x)^7.
a(n) = (n*(984 + 2650*n + 2685*n^2 + 1285*n^3 + 291*n^4 + 25*n^5)) / 720.
a(n) = 7*a(n-1) - 21*a(n-2) + 35*a(n-3) - 35*a(n-4) + 21*a(n-5) - 7*a(n-6) + a(n-7) for n>6.
(End)
MATHEMATICA
LinearRecurrence[{7, -21, 35, -35, 21, -7, 1}, {0, 11, 91, 406, 1316, 3486, 8022}, 40] (* or *) a = 1/720 (984 #1 + 2650 #1^2 + 2685 #1^3 + 1285 #1^4 + 291 #1^5 + 25 #1^6) &; Table[a[n], {n, 0, 40}]
Table[(25*n + 41)*Pochhammer[n, 5]/6!, {n, 0, 50}] (* G. C. Greubel, Oct 22 2017 *)
PROG
(PARI) for(n=0, 50, print1((25*n + 41)*(n+4)*(n+3)*(n+2)*(n+1)*n/6!, ", ")) \\ G. C. Greubel, Oct 22 2017
(PARI) concat(0, Vec(x*(11 + 14*x) / (1 - x)^7 + O(x^40))) \\ Colin Barker, Jul 28 2019
(Magma) [(25*n + 41)*(n+4)*(n+3)*(n+2)*(n+1)*n/Factorial(6):n in [0..50]]; // G. C. Greubel, Oct 22 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Peter Luschny, Oct 13 2017
STATUS
approved