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 A160567 a(n)=4*(a(n-1)a(n-3)-a(n-2)^2)/a(n-4), a(1)=a(2)=a(3)=1, a(4)=-4. 1
 1, 1, 1, -4, -20, -144, 704, 34816, 1101824, 12124160, -4499439616, -586464362496, -99309307559936, 33947352788107264, 26466630265219317760, 25787111566764821970944, -7045529183328701486465024 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,4 COMMENTS a(n+1) is the Hankel transform of A160565. LINKS MAPLE A160567 := proc(n)     option remember;     if n < 5 then         op(n, [1, 1, 1, -4]);     else         4*(procname(n-1)*procname(n-3)-procname(n-2)^2)/procname(n-4) ;     end if; end proc: # R. J. Mathar, Feb 25 2015 CROSSREFS Cf. A050512. Sequence in context: A187116 A098541 A004204 * A034216 A144009 A301270 Adjacent sequences:  A160564 A160565 A160566 * A160568 A160569 A160570 KEYWORD easy,sign AUTHOR Paul Barry, May 19 2009 STATUS approved

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Last modified March 18 17:51 EDT 2019. Contains 321292 sequences. (Running on oeis4.)