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%I #20 Jun 17 2017 03:04:37
%S 1,1,1,2,2,3,4,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,
%T 24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,
%U 47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72
%N G.f.: (1+x^5+x^10)/((1-x)*(1-x^3)).
%H G. Nebe, E. M. Rains and N. J. A. Sloane, <a href="http://neilsloane.com/doc/cliff2.html">Self-Dual Codes and Invariant Theory</a>, Springer, Berlin, 2006.
%H E. M. Rains and N. J. A. Sloane, Self-dual codes, pp. 177-294 of Handbook of Coding Theory, Elsevier, 1998 (<a href="http://neilsloane.com/doc/self.txt">Abstract</a>, <a href="http://neilsloane.com/doc/self.pdf">pdf</a>, <a href="http://neilsloane.com/doc/self.ps">ps</a>).
%H <a href="/index/Mo#Molien">Index entries for Molien series</a>
%H <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (2,-1).
%F Molien series is (1+x^10+x^20)/((1-x^2)*(1-x^6)).
%F a(n) = n - 3 for n > 7. [_Charles R Greathouse IV_, Oct 27 2011]
%t CoefficientList[Series[(1+x^5+x^10)/((1-x)*(1-x^3)),{x,0,80}],x] (* or *) LinearRecurrence[{2,-1},{1,1,1,2,2,3,4,4,5},80] (* _Harvey P. Dale_, Oct 11 2015 *)
%o (PARI) a(n)=if(n>7,n-3,[1, 1, 1, 2, 2, 3, 4, 4][n+1]) \\ _Charles R Greathouse IV_, Oct 27 2011
%K nonn,easy
%O 0,4
%A _N. J. A. Sloane_, Sep 06 2004
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