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0, 10, 300, 4500, 50000, 468750, 3937500, 30625000, 225000000, 1582031250, 10742187500, 70898437500, 457031250000, 2888183593750, 17944335937500, 109863281250000, 664062500000000, 3968811035156250, 23483276367187500
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history;
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OFFSET
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0,2
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LINKS
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Vincenzo Librandi, Table of n, a(n) for n = 0..1000
Index to sequences with linear recurrences with constant coefficients, signature (20,-150,500,-625).
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FORMULA
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G.f.: 10*x*(1 + 10*x)/(1 - 5*x)^4. - Vincenzo Librandi, Feb 12 2013
a(n) = 20*a(n-1)-150*a(n-2)+500*a(n-3)-625*a(n-4). - Vincenzo Librandi, Feb 12 2013
a(n) = 10*A081143(n+2)+100*A081143(n+1). [Bruno Berselli, Feb 13 2013]
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MATHEMATICA
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CoefficientList[Series[10 x (1 + 10 x)/(1 - 5 x)^4, {x, 0, 30}], x] (* Vincenzo Librandi, Feb 12 2013 *)
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PROG
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(MAGMA) [(n^3+n^2)*5^n: n in [0..25]]; /* or */ I:=[0, 10, 300, 4500]; [n le 4 select I[n] else 20*Self(n-1)-150*Self(n-2)+500*Self(n-3)-625*Self(n-4): n in [1..25]]; // Vincenzo Librandi, Feb 12 2013
(PARI) A129005(n)=5^n*(1+n)*n^2 \\ - M. F. Hasler, Feb 12 2013
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CROSSREFS
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Cf. A036289, A081143, A128796.
Sequence in context: A173479 A173478 A069672 * A162729 A221953 A152165
Adjacent sequences: A129002 A129003 A129004 * A129006 A129007 A129008
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KEYWORD
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nonn,easy
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AUTHOR
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Mohammad K. Azarian, May 01 2007
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EXTENSIONS
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Initial term a(0)=0 added by M. F. Hasler, Feb 12 2013
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STATUS
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approved
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