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%I A213565 #10 Jun 17 2017 03:53:57
%S A213565 1,21,127,467,1302,3038,6258,11754,20559,33979,53625,81445,119756,
%T A213565 171276,239156,327012,438957,579633,754243,968583,1229074,1542794,
%U A213565 1917510,2361710,2884635,3496311,4207581,5030137,5976552,7060312
%N A213565 Principal diagonal of the convolution array A213564.
%H A213565 Clark Kimberling, <a href="/A213565/b213565.txt">Table of n, a(n) for n = 1..1000</a>
%H A213565 <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (6,-15,20,-15,6,-1).
%F A213565 a(n) = (16*n^5 + 85*n^4  + 15*n^3 - 25*n^2 - n)/60.
%F A213565 a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 15*a(n-4) + 6*a(n-5) - a(n-6).
%F A213565 G.f.: x*(1 + 15*x + 16*x^2)/(1 - x)^6.
%t A213565 (See A213564.)
%Y A213565 Cf. A213564, A213500.
%K A213565 nonn,easy
%O A213565 1,2
%A A213565 _Clark Kimberling_, Jun 18 2012

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