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 A117251 Column 0 of triangle A117250. 1
 1, 1, -1, 4, -40, 896, -43008, 4325376, -899678208, 383862702080, -334114095890432, 590956713604022272, -2117988861556815822848, 15348576513041885002989568, -224527747847927003472304537600, 6621592717332784844802427579269120 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,4 LINKS FORMULA a(n) = (-1)^(n-1) * C(2*n,n)/(2*n-1) * 2^((n-1)*(n-2)/2-1). PROG (PARI) a(n)=(-1)^(n-1)*2^((n-1)*(n-2)/2-1)*binomial(2*n, n)/(2*n-1) CROSSREFS Sequence in context: A121276 A013053 A055128 * A220404 A211040 A012957 Adjacent sequences:  A117248 A117249 A117250 * A117252 A117253 A117254 KEYWORD sign AUTHOR Paul D. Hanna, Mar 14 2006 STATUS approved

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Last modified August 5 08:48 EDT 2021. Contains 346464 sequences. (Running on oeis4.)