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A287040
Triangle T(n,k) read by rows: coefficients of polynomials P_n(t) defined in Formula section.
3
0, 1, 1, 1, 1, 2, 5, 3, 2, 8, 17, 22, 10, 5, 29, 91, 106, 94, 35, 14, 140, 431, 701, 582, 396, 126, 42, 661, 2501, 4067, 4544, 2980, 1654, 462, 132, 3622, 14025, 27394, 31032, 26680, 14598, 6868, 1716, 429, 19993, 87947, 177018, 236940, 208780, 146862, 69356, 28396, 6435, 1430, 120909, 550811, 1245517, 1727148, 1776310, 1291654, 772422, 322204, 117016, 24310, 4862
OFFSET
0,6
LINKS
Gheorghe Coserea, Rows n=0..200, flattened
Pierre Lescanne, Quantitative aspects of linear and affine closed lambda terms, arXiv:1702.03085 [cs.DM], 2017.
FORMULA
y(x;t) = Sum_{n>=0} P_n(t)*x^n satisfies y = t + x*y^2 + x*deriv(y,t) + x*y, with y(0;t)=t, where P_n(t) = Sum_{k=0..n+1} T(n,k)*t^k.
A000108(n)=T(n,n+1), A001700(n)=T(n+1,n+1).
EXAMPLE
A(x;t) = t + (1 + t + t^2)*x + (2 + 5*t + 3*t^2 + 2*t^3)*x^2 + (8 + 17*t + 22*t^2 + 10*t^3 + 5*t^4)*x^3 + ...
Triangle starts:
n\k [0] [1] [2] [3] [4] [5] [6] [7] [8] [9]
[0] 0, 1;
[1] 1, 1, 1;
[2] 2, 5, 3, 2;
[3] 8, 17, 22, 10, 5;
[4] 29, 91, 106, 94, 35, 14;
[5] 140, 431, 701, 582, 396, 126, 42;
[6] 661, 2501, 4067, 4544, 2980, 1654, 462, 132;
[7] 3622, 14025, 27394, 31032, 26680, 14598, 6868, 1716, 429;
[8] 19993, 87947, 177018, 236940, 208780, 146862, 69356, 28396, 6435, 1430;
[9] ...
MATHEMATICA
nmax = 10; y[0, t_] := t; y[_, _] = 0;
Do[y[x_, t_] = Series[t + x y[x, t]^2 + x D[y[x, t], t] + x y[x, t], {x, 0, nmax}, {t, 0, nmax}] // Normal, {n, 0, nmax}];
CoefficientList[#, t]& /@ CoefficientList[y[x, t]+O[x]^nmax, x] // Flatten (* Jean-François Alcover, Dec 13 2018 *)
PROG
(PARI)
A287040_ser(N) = {
my(x='x+O('x^N), t='t, F0=t, F1=0, n=1);
while(n++,
F1 = t + x*F0^2 + x*deriv(F0, t) + x*F0;
if (F1 == F0, break()); F0 = F1; ); F0;
};
concat(apply(p->Vecrev(p), Vec(A287040_ser(10))))
\\ test: y=A287040_ser(50); y == t + x*y^2 + x*deriv(y, t) + x*y
CROSSREFS
Cf. A262301, A267827, A281270, A287030, A287045 (column 0).
Sequence in context: A156637 A195784 A279623 * A212887 A163766 A004200
KEYWORD
nonn,tabl
AUTHOR
Gheorghe Coserea, May 23 2017
STATUS
approved