An = Bn @ @¶ìÿa@óÝy‹¾a@ u@ @RUT
n Bn 8, 12, 16,…
n n≠0 17, 19, 21,…
14 ( ) 2( ) 1( ) 0 ()
ba [AHSME 1968] ( )
)a .a > b > 0
b (
14 ( ) 11 ( ) 10 ( ) 5 ()
3, x, y 3<x <y <9 [AHSME 1972] ( )
x +y . x, y, 9
11 1 ( ) 10 1 ( ) 10 ( ) 91 ()
4 4 2
2
[AMC10B, 2003] ( )
.6
3 ( ) − 3 ( ) −2 3 ( ) − 3 ()
33