A128784 a(n) = n^2*5^n.
0, 5, 100, 1125, 10000, 78125, 562500, 3828125, 25000000, 158203125, 976562500, 5908203125, 35156250000, 206298828125, 1196289062500, 6866455078125, 39062500000000, 220489501953125, 1235961914062500, 6885528564453125, 38146972656250000, 210285186767578125
Offset: 0
Links
- Harvey P. Dale, Table of n, a(n) for n = 0..1000
- Index entries for linear recurrences with constant coefficients, signature (15,-75,125).
Programs
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Mathematica
Table[n^2 5^n,{n,0,20}] (* or *) LinearRecurrence[{15,-75,125},{0,5,100},20] (* Harvey P. Dale, Dec 30 2011 *) -
PARI
a(n)=n^2*5^n \\ Charles R Greathouse IV, May 16 2018
Formula
From Harvey P. Dale, Dec 30 2011: (Start)
a(0)=0, a(1)=5, a(2)=100, a(n) = 15*a(n-1)-75*a(n-2)+125*a(n-3).
G.f.: -5*(5*x^2+x)/(5*x-1)^3. (End)