A134009 a(1) = 1; a(n+1) = round(sqrt(3)*a(n)).

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

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