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A120031 Numerators of reduced forms of fractions obtained by performing the first n divisions shown below. 30
1, 1, 2, 5, 40, 4, 48, 312, 1664, 14144, 56576, 28288, 226304, 217600, 870400, 2524160, 80773120, 2375680, 1900544, 35160064, 1406402560, 28831252480, 115325009920, 288312524800, 4613000396800, 92260007936, 369040031744 (list; graph; refs; listen; history; internal format)
OFFSET

0,3

COMMENTS

1

-------

2*3

..-----

..4*5

....---

....6*.....

In other words, the successive fractions are

1,

1

-,

2

1..4

----,

.23.

1..45.

------,

.23..6

1..45..8

--------,

.23..67.

and so on

Suggested by a question from Ciprian Bonciocat (6 years old).

FORMULA

a(n) = numerator of x(n) where x(0)=1, x(2n+1) = x(2n) (4n+1)/(4n+2), x(2n+2) = x(2n+1) (4n+4)/(4n+3) - Matthew Conroy Jun 26 2006

EXAMPLE

1, 1/2, 2/3, 5/9, 40/63, 4/7, ...

CROSSREFS

Cf. A120032.

Sequence in context: A067083 A183255 A109003 * A110066 A155176 A127974

Adjacent sequences:  A120028 A120029 A120030 * A120032 A120033 A120034

KEYWORD

nonn,frac

AUTHOR

Mihai Cipu (mihai.cipu(AT)imar.ro), Jun 05 2006

EXTENSIONS

More terms from Matthew Conroy Jun 26 2006

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Last modified February 15 08:20 EST 2012. Contains 205729 sequences.