procedure main(arglist)
local n
n := arglist[1] | 8    # limiting number of happy numbers to generate, default=8
writes("The first ",n," happy numbers are:")
every writes(" ", happy(seq()) \ n )
write()
end

procedure happy(i)    #: returns i if i is happy
local n

    if  4 ~= (0 <= i) then { # unhappy if negative, 0, or 4
        if i = 1 then return i
        every (n := 0) +:= !i ^ 2
        if happy(n) then return i
        }
end