A139085 - OEIS

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A139085

G.f. satisfies: 2*A(x) = 3*x + x^2 - Series_Reversion( A(x) ).

1, 1, -2, 15, -158, 2058, -31148, 529209, -9882430, 200035242, -4346788764, 100697241762, -2473869382964, 64191822293220, -1753530264442280, 50293662225989739, -1511101241900117982, 47467602491174747046 (list; graph; refs; listen; history; text; internal format)

	OFFSET	`1,3`
	LINKS	`Table of n, a(n) for n=1..18.`
	FORMULA	`a(n) = (1/2)(-1)^nA139086(n) for n>2 with a(1)=a(2)=1.`
	EXAMPLE	`G.f.: A(x) = x + x^2 - 2x^3 + 15x^4 - 158x^5 + 2058x^6 -+...` `Series_Reversion(A(x)) = x - x^2 + 4x^3 - 30x^4 + 316*x^5 -+...` `which equals -G(-x) where G(x) = g.f. of A139086.`
	PROG	`(PARI) {a(n)=local(A=x+x^2); if(n<1, 0, for(i=3, n+1, A=A-polcoeff(serreverse(A+xO(x^i)), i)x^i); polcoeff(A, n))}`
	CROSSREFS	`Cf. A139086.` `Sequence in context: A239107 A124548 A324463 * A268070 A204679 A259608` `Adjacent sequences: A139082 A139083 A139084 * A139086 A139087 A139088`
	KEYWORD	`sign`
	AUTHOR	`Paul D. Hanna, Apr 08 2008`
	STATUS	`approved`

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Last modified May 20 01:04 EDT 2022. Contains 353847 sequences. (Running on oeis4.)