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A192679 Floor-Sqrt transform of ordered Bell numbers (A000670). 0
1, 1, 1, 3, 8, 23, 68, 217, 738, 2662, 10111, 40281, 167605, 725850, 3262107, 15175084, 72908536, 361068922, 1839982245, 9633358049, 51746379547, 284824200163, 1604632175859, 9243292234736, 54390064543757, 326645626694244, 2000556362576213, 12485902607285611 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

Table of n, a(n) for n=0..27.

FORMULA

a(n) = floor(sqrt(orderedBell(n))).

MATHEMATICA

FSFromExpSeries[f_, x_, n_] := Map[Floor[Sqrt[#]]&, CoefficientList[Series[f, {x, 0, n}], x]Table[k!, {k, 0, n}]]

FSFromExpSeries[1/(2-Exp[x]), x, 40]

(* second program: *)

Fubini[n_, r_] := Sum[k!*Sum[(-1)^(i+k+r)*(i+r)^(n-r)/(i!*(k-i-r)!), {i, 0, k-r}], {k, r, n}]; Fubini[0, 1] = 1; a[n_] := Fubini[n, 1] // Sqrt // Floor; Table[a[n], {n, 0, 27}] (* Jean-François Alcover, Mar 30 2016 *)

CROSSREFS

Sequence in context: A025262 A056010 A002712 * A193418 A005960 A273716

Adjacent sequences:  A192676 A192677 A192678 * A192680 A192681 A192682

KEYWORD

nonn

AUTHOR

Emanuele Munarini, Jul 07 2011

STATUS

approved

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Last modified November 21 14:18 EST 2019. Contains 329371 sequences. (Running on oeis4.)