I want to pass several values to a function which is located on a
server (so I can't change its behavior).
That function only accepts five values which must be ints.

There are several lists:
a = [1, 2, 3, 4, 5]
b = [5, 4, 3, 2, 1]
c = [0, 0, 0, 0, 0]

I want to pass each value from these lists to that function.
What is the most pythonic way?

This wouldn't work because we're passing a list not ints:
function(a)
function(b)
function(c)

This wouldn't work too (the reason is the same):
def foo(x):
  return x[0], x[1], x[2], x[3], x[4], x[5]

function(foo(a))
function(foo(b))
function(foo(c))

This would work, but it's not pythonic at all (imagine that you want
to call it 10 times or even more).

function(a[0], a[1], a[2], a[3], a[4], a[5])
function(b[0], b[1], b[2], b[3], b[4], b[5])
function(c[0], c[1], c[2], c[3], c[4], c[5])

function(*a)  # like function(a[0], a[1], a[2], ...)

If you have many lists, use a for-loop:

for L in (a, b, c):
    function(*L)

def five(func, args):
   a, b, c, d, e = args
   return func(a, b, c, d, e)

five(function, a)
five(function, b)
five(function, c)

for args in argses:
   five(function, args)

py> L5 = [1, 2, 3, 4, 5]
py> L4 = [1, 2, 3, 4]
py> def f4(a,b,c,d):
        print a,b,c,d
py> def f5(a,b,c,d,e):
        print a,b,c,d,e
py> def apply_five(func, args):
        a, b, c, d, e = args
        return func(a, b, c, d, e)
py> apply_five(f5, L5)
1 2 3 4 5
py> apply_five(f5, L4)
ValueError: need more than 4 values to unpack
#
# Try this instead:
#
py> def apply_arglst(func, arglst):
        return func(*arglst)
py> apply_arglst(f4,L4)
1 2 3 4
py> apply_arglst(f5,L5)
1 2 3 4 5