Tough Sequence problem

[darkmass]

Find a formula for the givin sequence:

0, 1 , 1 , 2 , 2 , 3 ,3 ,4 ,4 ............


thanks. any help would be appreciated.

[cookiemonster]

a_{2n} = a_{2n-2} + 1
a_{2n+1} = a_{2n-1} + 1
a_0 = 0
a_1 = 1

cookiemonster

[Muzza]

Or a_n = floor( (n + 1)/2 ), n >= 0.