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 A090901 a(n) = floor[geometric mean of first n factorials]. 2
 1, 1, 2, 4, 8, 17, 38, 91, 230, 605, 1661, 4735, 13998, 42795, 135021, 438826, 1466690, 5033778, 17716515, 63865399, 235547709, 887938469, 3418054843, 13424588130, 53753996494, 219278318407, 910679550679, 3848136018924, 16534775039068, 72206065899240 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS Peter Luschny and Jon E. Schoenfield, Table of n, a(n) for n = 1..871 (First 100 terms from Peter Luschny) FORMULA a(n) = floor(A000178(n)^(1/n)). MAPLE seq(floor(evalf((product(k!, k=1..n))^(1/n))), n=1..30); # (Deutsch) WARNING Gives wrong answers! - N. J. A. Sloane, Nov 27 2015 a := n -> mul(k!^(1/n), k=1..n): prec := n -> max(10, ceil(log(2*Pi*n)/2+n*(log(n/exp(1))))): seq(floor(evalf(a(n), prec(n))), n=1..100); # Peter Luschny, Nov 27 2015 MATHEMATICA Module[{nn=30, fs}, fs=Range[nn]!; Table[Floor[GeometricMean[Take[fs, n]]], {n, nn}]] (* Harvey P. Dale, Nov 27 2015 *) PROG (PARI) a(n) = default(realprecision, 2*n); floor(prod(i=2, n, i!)^(1/n)); vector(500, n, a(n)) \\ Altug Alkan, Nov 27 2015 (MAGMA) a:=[]; f:=1; P:=1; for n in [1..100] do f*:=n; P*:=f; g:=Floor(P^(1/n)); while true do d:=g^n-P; if d gt 0 then g-:=Ceiling((1.0*d)*g/P/n); else d:=P-(g+1)^n; if d ge 0 then g+:=Ceiling((1.0*d)*g/P/n); else break; end if; end if; end while; a[n]:=g; end for; a; // Jon E. Schoenfield, Nov 27 2015 (Sage) def a(n): # Throws an error if result could not be computed exactly.     prec = max(53, ceil(0.75*ceil((log(2*pi*n)/2+n*(log(n/exp(1)))))))     rif = RealIntervalField(prec)     r = rif(prod(factorial(k)^(1/n) for k in (1..n)))     return r.unique_floor() [a(n) for n in (1..100)] # Peter Luschny, Nov 28 2015 CROSSREFS Cf. A090902. Sequence in context: A003007 A086615 A081124 * A101516 A118928 A049312 Adjacent sequences:  A090898 A090899 A090900 * A090902 A090903 A090904 KEYWORD nonn AUTHOR Amarnath Murthy, Dec 12 2003 EXTENSIONS Corrected and extended by N. J. A. Sloane, Oct 26 2004 More terms from Emeric Deutsch, Apr 13 2005 Corrected by Harvey P. Dale, Nov 27 2015 STATUS approved

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Last modified October 21 09:27 EDT 2018. Contains 316408 sequences. (Running on oeis4.)