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A093333 a(0) = 0, a(1) = 1 and for n >= 0, a(n+2) = floor(2 * sqrt(a(n) * a(n+1))). 2
0, 1, 1, 2, 2, 4, 5, 8, 12, 19, 30, 47, 75, 118, 188, 297, 472, 748, 1188, 1885, 2992, 4749, 7538, 11966, 18994, 30151, 47861, 75975, 120602, 191444, 303898, 482408, 765774, 1215591, 1929629, 3063096, 4862361, 7718517, 12252381, 19449443, 30874065 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

COMMENTS

A geometric-mean analog of the Fibonacci sequence.

LINKS

Table of n, a(n) for n=0..40.

FORMULA

a(n) = c*2^(2n/3)+O(1) where c = 0.4600594211686036392470119450103830526110335102224661416117198000442511705774434976470174973885560.... - Benoit Cloitre, Dec 17 2006

EXAMPLE

a(5) = 4 because a(5) = int(sqrt(a(3) * a(4))) = int(2 * sqrt(2*2)) = int(2 * sqrt(4)) = 4.

MATHEMATICA

Join[{0}, RecurrenceTable[{a[1]==a[2]==1, a[n]==Floor[2Sqrt[a[n-1]a[n-2]]]}, a, {n, 40}]] (* Harvey P. Dale, Jun 14 2014 *)

CROSSREFS

Cf. A000045, A093332, A093335.

Sequence in context: A274153 A079501 A093335 * A116085 A216198 A085570

Adjacent sequences:  A093330 A093331 A093332 * A093334 A093335 A093336

KEYWORD

easy,nonn

AUTHOR

Robert A. Stump (rstump_2004(AT)yahoo.com), Apr 25 2004

STATUS

approved

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Last modified January 20 06:07 EST 2019. Contains 319323 sequences. (Running on oeis4.)