convert number Verilog

Hello

Don't remember as an operation is called and and therefore i have 
problems with the search for implementation.

input [4:0] number1,
output [31:0] number2

number2  has the form :  11..1100..00  where the cout of "1" is equal to 
the number1
As example number1 = 3, so number2 = 111000..00
As example number1 = 8, so number2 = 11111111000..00

I think the best way to speed and energy efficiency is to describe each 
output bit, but for large numbers it looks unattractive for reading and 
understanding. I would like to find a parametrized short record of this 
relationship, but I can not

Thanks for the help