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a(n) = 2*a(n-1) + a(n-2) - a(n-4) - a(n-5) - a(n-6) - a(n-7).
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%I #8 Feb 11 2016 08:02:11

%S 2,5,12,28,65,150,346,795,1826,4192,9621,22078,50660,116239,266704,

%T 611930,1404013,3221358,7391048,16957921,38908004,89269924,204819503,

%U 469934590,1078210352,2473828397,5675911794,13022719964

%N a(n) = 2*a(n-1) + a(n-2) - a(n-4) - a(n-5) - a(n-6) - a(n-7).

%D R. K. Guy, personal communication.

%H <a href="/index/Rec#order_07">Index entries for linear recurrences with constant coefficients</a>, signature (2,1,0,-1,-1,-1,-1).

%F G.f.: ( -(x-1)*(x^4+2*x^3+3*x^2+3*x+2) ) / ( 1-2*x-x^2+x^4+x^5+x^6+x^7 ). - _R. J. Mathar_, Feb 11 2016

%Y Matches A018914 up to n<=6.

%K nonn,easy

%O 0,1

%A _N. J. A. Sloane_.