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A055610 A companion sequence to A011896. 1

%I

%S 0,0,0,1,2,5,9,15,24,36,52,71,95,123,156,195,240,292,350,416,489,570,

%T 660,759,868,986,1115,1254,1404,1566,1740,1927,2126,2339,2565,2805,

%U 3060,3330,3616,3917,4235,4569,4920,5289,5676,6082,6506,6950,7413,7896

%N A companion sequence to A011896.

%H <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (3, -3, 1, 0, 0, 0, 1, -3, 3, -1).

%F G.f.: x^3 * (1 - x + 2*x^2 - x^3 + x^4 + x^5) / ((1 - x)^3 * (1 - x^7)).

%F a(n) = -A011896(2 - n).

%e x^3 + 2*x^4 + 5*x^5 + 9*x^6 + 15*x^7 + 24*x^8 + 36*x^9 + 52*x^10 + ...

%o (PARI) {a(n) = ceil( n * (n-1) * (n-2) / 14)}

%Y Cf. A011896.

%K nonn

%O 0,5

%A _Michael Somos_, Jun 02 2000

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Last modified June 17 22:14 EDT 2021. Contains 345086 sequences. (Running on oeis4.)