A179389 - OEIS

A179389

The number of sorted length n integer sequences with mean zero and sample standard deviation n.

0, 1, 2, 6, 55, 360, 3035, 20502, 160077, 1369317

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OFFSET

2,3

LINKS

Table of n, a(n) for n=2..11.

MATHEMATICA

Clear[f, g, a, n, s, ss]; f[0, 0, 0] := {{}}; f[0, s_, ss_] := {}; f[n_, s_, ss_] := f[n, s, ss] = Union[ Sort /@ Apply[Join, Table[Map[Append[ #, i] &, f[n - 1, s - i, ss - i^2]], {i, -Floor[Sqrt[ss]], Floor[Sqrt[ss]]}]]]; g[n_, s_] := f[n, 0, s^2 (n - 1)]; a[n_] := Length[g[n, n]]; Table[a[n], {n, 2, 7}]

CROSSREFS

Sequence in context: A267348 A264610 A153450 * A084123 A193473 A336899

Adjacent sequences: A179386 A179387 A179388 * A179390 A179391 A179392

KEYWORD

nonn,more

AUTHOR

Todd Will (will.todd(AT)uwlax.edu), Jul 12 2010

EXTENSIONS

a(10) & a(11) from Robert G. Wilson v, Jul 24 2010

STATUS

approved