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A021774
Expansion of 1/((1-x)(1-4x)(1-5x)(1-10x)).
1
1, 20, 271, 3150, 34041, 354480, 3620611, 36607010, 368161981, 3692428740, 36979730151, 370080107670, 3702237477121, 37029646251800, 370333177834891, 3703516786589130, 37036098633715461, 370365663082767660
OFFSET
0,2
FORMULA
G.f.: 1/((1-x)*(1-4*x)*(1-5*x)*(1-10*x)).
a(n) = -1/108 +2^(2n+5)/9 -5^(n+2)/4 +10^(n+2)/27. [Bruno Berselli, May 08 2013]
MATHEMATICA
CoefficientList[Series[1/((1 - x) (1 - 4 x) (1 - 5 x) (1 - 10 x)), {x, 0, 20}], x] (* Bruno Berselli, May 08 2013 *)
PROG
(PARI) Vec(1/((1-x)*(1-4*x)*(1-5*x)*(1-10*x))+O(x^20)) \\ Bruno Berselli, May 08 2013
(Magma) m:=20; R<x>:=PowerSeriesRing(Integers(), m); Coefficients(R!(1/((1-x)*(1-4*x)*(1-5*x)*(1-10*x)))); // Bruno Berselli, May 08 2013
CROSSREFS
Cf. A018912 (first differences).
Sequence in context: A021594 A224248 A019793 * A181384 A269009 A307038
KEYWORD
nonn,easy
AUTHOR
STATUS
approved