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A089796
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Series reversion of g.f. A(x) is -A(-x).
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1
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1, 1, 1, 2, 4, 8, 17, 38, 87, 203, 482, 1160, 2822, 6929, 17149, 42736, 107144, 270060, 683940, 1739511, 4441255, 11378814, 29245927, 75386341, 194838673, 504802508, 1310843123, 3411070838, 8893590454, 23230151872, 60780378423, 159281034709
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,4
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FORMULA
| G.f. A(x)=y satisfies (x-x^2-x^3)+y*(-1+3*x-x^3)+y^2*(-1+x^2-x^3)+y^3*(1-x+x^2-x^3)=0.
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PROG
| (PARI) a(n)=local(A); if(n<1, 0, A=O(x); for(k=1, n, A=(x-x^2-x^3)+A*(3*x-x^3)+A^2*(-1+x^2-x^3)+A^3*(1-x+x^2-x^3)); polcoeff(A, n))
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CROSSREFS
| a(n) = A006196(n) if n<28.
Sequence in context: A154222 A114199 A006196 * A112482 A193050 A107597
Adjacent sequences: A089793 A089794 A089795 * A089797 A089798 A089799
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KEYWORD
| nonn
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AUTHOR
| Michael Somos, Nov 10 2003
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