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 A144580 Denominators of expansion of exp(1-sqrt(1-x-x^2)). 2
 1, 2, 4, 48, 384, 640, 46080, 645120, 1720320, 185794560, 3715891200, 1946419200, 1961990553600, 7287393484800, 238054853836800, 42849873690624000, 1371195958099968000, 7770110429233152000, 239763407530622976000, 63777066403145711616000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS D-finite with recurrence: Expansion satisfies 8*a(n)+12*a(n+1)+(22+8*n^2+24*n)*a(n+2)+(73+12*n^2+60*n)*a(n+3)+(-18*n-8-4*n^2)*a(n+4)+(-4*n^2-36*n-80)*a(n+5)=0. - Robert Israel, Dec 31 2019 LINKS Robert Israel, Table of n, a(n) for n = 0..403 EXAMPLE The expansion is 1 + (1/2)*x + (3/4)*x^2 + (31/48)*x^3 + (301/384)*x^4 + (571/640)*x^5 + (51751/46080)*x^6 + ( 926731/645120)*x^7 + (3281851/1720320)*x^8 + ... MAPLE g:= gfun:-rectoproc({8*a(n)+12*a(n+1)+(22+8*n^2+24*n)*a(n+2)+(73+12*n^2+60*n)*a(n+3)+(-18*n-8-4*n^2)*a(n+4)+(-4*n^2-36*n-80)*a(n+5), a(0) = 1, a(1) = 1/2, a(2) = 3/4, a(3) = 31/48, a(4) = 301/384}, a(n), remember): seq(denom(g(n)), n=0..40); # Robert Israel, Dec 31 2019 CROSSREFS Cf. A144579. Sequence in context: A088301 A212429 A298903 * A144578 A143968 A308665 Adjacent sequences: A144577 A144578 A144579 * A144581 A144582 A144583 KEYWORD nonn,frac AUTHOR N. J. A. Sloane, Jan 07 2009 STATUS approved

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Last modified March 29 22:15 EDT 2023. Contains 361599 sequences. (Running on oeis4.)