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 (6,-15,20,-15,6,-1).
FORMULA
a(n) = n*Stirling2(3 + n, 1 + n).
-a(-n-3) = (n + 3)*abs(Stirling1(n+2, n)) for n >= 0.
-a(-n-3) = a(n) + binomial(n+3, 4) for n >= 0.
From Colin Barker, Nov 21 2017: (Start)
G.f.: x*(7 + 8*x) / (1 - x)^6.
a(n) = n*(24 + 62*n + 57*n^2 + 22*n^3 + 3*n^4)/24.
a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 15*a(n-4) + 6*a(n-5) - a(n-6) for n>5. (End)
MATHEMATICA
LinearRecurrence[{6, -15, 20, -15, 6, -1}, {0, 7, 50, 195, 560, 1330}, 32]
Table[n*StirlingS2[n+3, n+1], {n, 0, 50}] (* G. C. Greubel, Nov 20 2017 *)
f[n_] := (3n + 4) Pochhammer[n, 4]/4!; Array[f, 35, 0] (* or *)
CoefficientList[ Series[ x (7 + 8x)/(1 - x)^6, {x, 0, 34}], x] (* Robert G. Wilson v, Nov 21 2017 *)
PROG
(PARI) for(n=0, 30, print1(n*Stirling(n+3, n+1, 2), ", ")) \\ G. C. Greubel, Nov 20 2017
(Magma) [0] cat [(3*n + 4)*Factorial(n+3)/(Factorial(n-1)*Factorial(4)): n in [1..30]]; // G. C. Greubel, Nov 20 2017
(PARI) concat(0, Vec(x*(7 + 8*x) / (1 - x)^6 + O(x^40))) \\ Colin Barker, Nov 21 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Peter Luschny, Oct 20 2017
STATUS
approved