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%I #15 Sep 29 2022 11:49:39
%S 1,20,257,2704,25389,221676,1841449,14758568,115171397,880623172,
%T 6627177921,49248518592,362296167325,2643446894108,19158543110873,
%U 138087153497176,990728497913973,7081081591668084
%N Expansion of 1/((1-2x)(1-5x)(1-6x)(1-7x)).
%H <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (20,-143,424,-420).
%F a(n) = -2*2^n/15 + 125*5^n/6 - 54*6^n/1 + 343*7^n/10. - _R. J. Mathar_, Jun 20 2013
%F E.g.f.: exp(2*x)*(1029*exp(5*x) - 1620*exp(4*x) + 625*exp(3*x) - 4)/30. - _Stefano Spezia_, Sep 29 2022
%t CoefficientList[Series[1/((1-2x)(1-5x)(1-6x)(1-7x)),{x,0,20}],x] (* or *) LinearRecurrence[{20,-143,424,-420},{1,20,257,2704},20] (* _Harvey P. Dale_, Oct 10 2017 *)
%Y Cf. A028027, A028032.
%K nonn,easy
%O 0,2
%A _N. J. A. Sloane_
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