%I #13 Oct 24 2019 18:20:08

%S 1,4,14,36,103,248,684,1624,4445,10524,28762,68060,185955,439984,

%T 1202072,2844144,7770361,18384884,50228454,118841812,324681887,

%U 768205608,2098776772,4965759176,13566706389,32099171980,87696568754,207492309516,566879531803

%N a(n) = Sum_{0<=j<=i<=n} A027157(i, j).

%H Colin Barker, <a href="/A027166/b027166.txt">Table of n, a(n) for n = 0..1000</a>

%H <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (2,5,-12,9,-6,3).

%F From _Colin Barker_, Feb 20 2016: (Start)

%F a(n) = 2*a(n-1)+5*a(n-2)-12*a(n-3)+9*a(n-4)-6*a(n-5)+3*a(n-6) for n>5.

%F G.f.: (1+x)^2 / ((1-x)^2*(1-6*x^2-3*x^4)).

%F (End)

%t LinearRecurrence[{2,5,-12,9,-6,3},{1,4,14,36,103,248},30] (* _Harvey P. Dale_, Apr 18 2019 *)

%o (PARI) Vec((1+x)^2/((1-x)^2*(1-6*x^2-3*x^4)) + O(x^40)) \\ _Colin Barker_, Feb 20 2016

%Y Partial sums of A027164.

%K nonn,easy

%O 0,2

%A _Clark Kimberling_