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 A113180 Expansion of 1/sqrt((1-2x)^2-8x^4). 0
 1, 2, 4, 8, 20, 56, 160, 448, 1240, 3440, 9632, 27200, 77216, 219840, 627200, 1793024, 5136480, 14743232, 42390400, 122064640, 351951232, 1015990528, 2936079360, 8493340672, 24591589120, 71262291456, 206666232832, 599778166784 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS In general, 1/sqrt((1-a*x)^2-4*b*x^4) expands to sum{k=0..floor(n/2), C(n-2k,k)C(n-3k,k)b^k*a^(n-4k)}. LINKS FORMULA a(n)=sum{k=0..floor(n/2), C(n-2k, k)C(n-3k, k)2^(n-3k)}. CROSSREFS Cf. A098482, A113179. Sequence in context: A000980 A123611 A082279 * A000116 A006407 A100447 Adjacent sequences:  A113177 A113178 A113179 * A113181 A113182 A113183 KEYWORD easy,nonn AUTHOR Paul Barry, Oct 16 2005 STATUS approved

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