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A134009 a(1) = 1; a(n+1) = round(sqrt(3)*a(n)). 1
1, 2, 3, 5, 9, 16, 28, 48, 83, 144, 249, 431, 747, 1294, 2241, 3882, 6724, 11646, 20171, 34937, 60513, 104812, 181540, 314437, 544621, 943311, 1633863, 2829934, 4901589, 8489801, 14704767, 25469404, 44114302, 76408212, 132342905, 229224635, 397028714 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Chai Wah Wu, Table of n, a(n) for n = 1..1000

EXAMPLE

a(6) = 16 because a(5) is 9 and round(sqrt(3)*9) = 16.

MATHEMATICA

With[{c=Sqrt[3]}, NestList[Floor[c #+1/2]&, 1, 45]] (* Harvey P. Dale, May 03 2011 *)

PROG

(Python)

from gmpy2 import isqrt_rem

A134009_list = [1]

for _ in range(1000):

    i, j = isqrt_rem(3*A134009_list[-1]**2)

    A134009_list.append(int(i+ int(4*(j-i) >= 1))) # Chai Wah Wu, Aug 16 2016

CROSSREFS

Sequence in context: A291311 A017914 A137402 * A018160 A079960 A005314

Adjacent sequences:  A134006 A134007 A134008 * A134010 A134011 A134012

KEYWORD

easy,nonn

AUTHOR

Ben Paul Thurston, Jan 09 2008

EXTENSIONS

More terms from Harvey P. Dale, May 03 2011

STATUS

approved

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Last modified April 10 02:39 EDT 2020. Contains 333392 sequences. (Running on oeis4.)