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 A203151 (n-1)-st elementary symmetric function of {1,1,2,2,3,3,4,4,5,5,...,Floor[(n+1)/2]}. 1
 1, 2, 5, 12, 40, 132, 564, 2400, 12576, 65760, 408960, 2540160, 18299520, 131725440, 1079205120, 8836853760, 81157386240, 745047797760, 7582159872000, 77138417664000, 861690783744000, 9623448705024000, 117074735382528000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS EXAMPLE Let esf abbreviate "elementary symmetric function".  Then 0th esf of {2}:  1 1st esf of {1,1}:  1+1=2 2nd efs of {1,1,2} is 1*1+1*2+1*2=5 MATHEMATICA f[k_] := Floor[(k + 1)/2]; t[n_] := Table[f[k], {k, 1, n}] a[n_] := SymmetricPolynomial[n - 1, t[n]] Table[a[n], {n, 1, 22}] (* A203151 *) CROSSREFS Cf. A203152. Sequence in context: A050258 A051436 A054581 * A140440 A005664 A009739 Adjacent sequences:  A203148 A203149 A203150 * A203152 A203153 A203154 KEYWORD nonn AUTHOR Clark Kimberling, Dec 29 2011 STATUS approved

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