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a(n) = 3*a(n-1) - a(n-2) + 2*a(n-3) - 2*a(n-4).
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%I #8 May 13 2019 10:11:57

%S 2,6,17,48,135,379,1064,2987,8385,23538,66075,185483,520680,1461631,

%T 4103029,11517850,32332423,90762215,254783864,715218523,2007731289,

%U 5636018642,15821193955,44412588755,124673147016,349977202919

%N a(n) = 3*a(n-1) - a(n-2) + 2*a(n-3) - 2*a(n-4).

%D R. K. Guy, personal communication.

%H <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (3,-1,2,-2).

%F G.f.: ( 2+x^2-x^3 ) / ( 1-3*x+x^2-2*x^3+2*x^4 ). - _R. J. Mathar_, Feb 11 2016

%t LinearRecurrence[{3,-1,2,-2},{2,6,17,48},30] (* _Harvey P. Dale_, May 13 2019 *)

%Y Cf. A018915.

%K nonn,easy

%O 0,1

%A _N. J. A. Sloane_.