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A055329
Number of rooted identity trees with n nodes and 4 leaves.
2
2, 11, 40, 109, 254, 524, 998, 1774, 2995, 4833, 7525, 11346, 16659, 23877, 33528, 46203, 62637, 83643, 110213, 143432, 184600, 235129, 296687, 371072, 460382, 566866, 693121, 841917, 1016422, 1220001, 1456473, 1729878, 2044767, 2405940
OFFSET
8,1
FORMULA
G.f.: x^8*(2+5*x+9*x^2+8*x^3+5*x^4+x^6)/((1-x)^7*(1+x)^3*(1+x^2)*(1+x+x^2)) - Colin Barker, Nov 07 2012
a(n) = -[n=0] + (60*n^6 -1236*n^5 +9450*n^4 -33520*n^3 +59940*n^2 -66294*n +48065)/69120 +(-1)^n*(4*n^2 -38*n +89)/512 +(3/32)*(-1)^floor((n+1)/2) + ChebyshevU(n, -1/2)/27. - G. C. Greubel, Nov 09 2023
MATHEMATICA
Drop[CoefficientList[Series[x^8*(2+5*x+9*x^2+8*x^3+5*x^4+x^6)/((1-x)^3*(1-x^2)^2*(1-x^3)*(1-x^4)), {x, 0, 50}], x], 8] (* G. C. Greubel, Nov 09 2023 *)
PROG
(PARI) Vec((2 + 5*x + 9*x^2 + 8*x^3 + 5*x^4 + x^6)/((1 - x)^7*(1 + x)^3*(1 + x^2)*(1 + x + x^2)) + O(x^40)) \\ Andrew Howroyd, Aug 28 2018
(Magma) R<x>:=PowerSeriesRing(Integers(), 50); Coefficients(R!( x^8*(2+5*x+9*x^2+8*x^3+5*x^4+x^6)/((1-x)^3*(1-x^2)^2*(1-x^3)*(1-x^4)) )); // G. C. Greubel, Nov 09 2023
(SageMath)
def A055329_list(prec):
P.<x> = PowerSeriesRing(ZZ, prec)
return P( x^8*(2+5*x+9*x^2+8*x^3+5*x^4+x^6)/((1-x)^3*(1-x^2)^2*(1-x^3)*(1-x^4)) ).list()
a=A055329_list(50); a[8:] # G. C. Greubel, Nov 09 2023
CROSSREFS
Column 4 of A055327.
Sequence in context: A125064 A361493 A274326 * A193005 A152895 A308524
KEYWORD
nonn,easy
AUTHOR
Christian G. Bower, May 12 2000
STATUS
approved