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A304454 G.f. satisfies: A(x) = 1 / (1/x - 1 - A(A(x))), with A(0) = 0. 0
0, 1, 1, 2, 5, 15, 51, 191, 773, 3338, 15243, 73131, 366815, 1916260, 10394665, 58404853, 339223859, 2033188222, 12556915219, 79807729238, 521399203037, 3497978659977, 24076009827669, 169865542733652, 1227553152971419, 9079751310622581, 68692742886823205 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,4
LINKS
FORMULA
a(n) = A193296(n+1) if n>0.
EXAMPLE
G.f. = x + x^2 + 2*x^3 + 5*x^4 + 15*x^5 + 51*x^6 + 191*x^7 + 773*x^8 + 3338*x^9 + ...
MATHEMATICA
a[ n_] := If[n < 0, 0, SeriesCoefficient[ Nest[ 1 / (1/x - 1 - (# /. x -> #)) &, O[x], Ceiling[n/2]], {x, 0, n}]];
PROG
(PARI) {a(n) = my(A); if( n<0, 0, A = O(x); forstep(k=1, n, 2, A = 1 / (1/x - 1 - subst(A, x, A))); polcoeff(A, n))};
CROSSREFS
Cf. A193296.
Sequence in context: A108307 A275605 A193296 * A287253 A117426 A201168
KEYWORD
nonn
AUTHOR
Michael Somos, May 12 2018
STATUS
approved

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Last modified May 29 20:11 EDT 2024. Contains 372952 sequences. (Running on oeis4.)