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A361771 Expansion of g.f. A(x) satisfying 1 = Sum_{n=-oo..+oo} x^n * (2*A(x) - (-x)^n)^(n-1).

%I A361771 #9 Apr 22 2025 21:55:57
%S A361771 1,1,1,7,28,89,421,1898,7912,36412,169960,779139,3668210,17486938,
%T A361771 83333003,400956919,1943928504,9455346485,46225027071,227066384875,
%U A361771 1119123274755,5534782142253,27463607765186,136652474592260,681728348606011,3409395265172439,17088672210734316
%N A361771 Expansion of g.f. A(x) satisfying 1 = Sum_{n=-oo..+oo} x^n * (2*A(x) - (-x)^n)^(n-1).
%H A361771 Paul D. Hanna, <a href="/A361771/b361771.txt">Table of n, a(n) for n = 0..300</a>
%F A361771 G.f. A(x) = Sum_{n>=0} a(n)*x^n may be defined by the following.
%F A361771 (1) 1 = Sum_{n=-oo..+oo} x^n * (2*A(x) - (-x)^n)^(n-1).
%F A361771 (2) 1 = Sum_{n=-oo..+oo} (-1)^(n+1) * x^(n^2) / (1 - 2*A(x)*(-x)^n)^(n+1).
%e A361771 G.f.: A(x) = 1 + x + x^2 + 7*x^3 + 28*x^4 + 89*x^5 + 421*x^6 + 1898*x^7 + 7912*x^8 + 36412*x^9 + 169960*x^10 + 779139*x^11 + 3668210*x^12 + ...
%o A361771 (PARI) {a(n) = my(A=[1]); for(i=1, n, A=concat(A, 0);
%o A361771 A[#A] = polcoeff( sum(m=-#A, #A, x^m * (2*Ser(A) - (-x)^m)^(m-1) ), #A-1)/2); A[n+1]}
%o A361771 for(n=0, 30, print1(a(n), ", "))
%Y A361771 Cf. A361772, A361773, A361774.
%Y A361771 Cf. A355865, A357227, A359712, A357232.
%K A361771 nonn
%O A361771 0,4
%A A361771 _Paul D. Hanna_, May 13 2023