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A275751
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Self-convolution square root of the even bisection of A274965.
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3
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1, 1, 4, 19, 92, 446, 2150, 10280, 48761, 229558, 1073278, 4986624, 23037102, 105877968, 484337300, 2206188412, 10010589904, 45264063504, 204016241794, 916898737038, 4109984712933, 18379240912034, 82012499946246, 365245641944278, 1623757696702586, 7207073607368924, 31941896126213722, 141377838141158888, 624983649220555836, 2759711619634526196, 12173102200970091434
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OFFSET
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0,3
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COMMENTS
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The g.f. of A274965 equals G(x,1), where G(x,y) = x*y + G(x,x*y)^2 is the g.f. of A275670.
First negative term is at a(646).
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LINKS
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EXAMPLE
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G.f.: A(x) = 1 + x + 4*x^2 + 19*x^3 + 92*x^4 + 446*x^5 + 2150*x^6 + 10280*x^7 + 48761*x^8 + 229558*x^9 + 1073278*x^10 + 4986624*x^11 + 23037102*x^12 +...
where
A(x)^2 = 1 + 2*x + 9*x^2 + 46*x^3 + 238*x^4 + 1228*x^5 + 6289*x^6 + 31924*x^7 + 160694*x^8 + 802642*x^9 + 3980916*x^10 +...+ A274965(2*n)*x^n +...
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PROG
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(PARI) {a(n) = my(A, B=1); for(k=0, 2*n, B = B^2 + x^(2*n+1-k) +O(x^(2*n+1))); A = sqrt( (B + subst(B, x, -x))/2 ); polcoeff(A, 2*n)}
for(n=0, 30, print1(a(n), ", "))
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CROSSREFS
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KEYWORD
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sign
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AUTHOR
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STATUS
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approved
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