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 A147682 Late-growing permutations: number of permutations of 2 indistinguishable copies of 1..n with every partial sum <= the same partial sum averaged over all permutations. 2
 1, 1, 2, 30, 403, 18720, 746192, 71892912, 5873837638, 951265850580, 133244998049858, 32484245570649180, 6956417433946216990, 2375465385671586163800, 723157816455776560763294, 329255781245519867317200240, 135189844328107458501296074066, 79079768375837127458516103725820 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS MAPLE b:= proc(l) option remember; local m, n, g;       m, n:= nops(l), add(i, i=l);       g:= add(i*l[i], i=1..m)-(m+1)/2*(n-1);      `if`(n<2, 1, add(`if`(l[i]>0 and i<=g,         b(subsop(i=l[i]-1, l)), 0), i=1..m))     end: a:= n-> b([2\$n]): seq(a(n), n=1..10);  # Alois P. Heinz, Aug 16 2012 MATHEMATICA b[l_List] := b[l] = Module[{m, n, g}, {m, n} = {Length[l], Total[l]}; g = Sum[i* l[[i]], {i, 1, m}] - (m+1)/2*(n-1); If[n<2, 1, Sum[If[l[[i]]>0 && i <= g, b[ ReplacePart[l, i -> l[[i]]-1]], 0], {i, 1, m}]]]; a[n_] := b[Table[2, {n}]]; Table[a[n], {n, 0, 10}] (* Jean-François Alcover, Mar 13 2015, after Alois P. Heinz *) CROSSREFS Cf. A147681. Column k=2 of A215561. Sequence in context: A083446 A230726 A091345 * A211906 A077517 A060042 Adjacent sequences:  A147679 A147680 A147681 * A147683 A147684 A147685 KEYWORD nonn,hard AUTHOR R. H. Hardin, May 01 2009 EXTENSIONS a(14) from Alois P. Heinz, Aug 16 2012 a(15) from Alois P. Heinz, Nov 02 2014 a(16) from Vaclav Kotesovec, Sep 07 2016 a(17) from Vaclav Kotesovec, Sep 08 2016 STATUS approved

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Last modified February 20 14:56 EST 2019. Contains 320327 sequences. (Running on oeis4.)