How to create nested Lua tables using the C API

I want to create a table like

myTable = {
    [0] = { ["a"] = 4, ["b"] = 2 },
    [1] = { ["a"] = 13, ["b"] = 37 }
}

using the C API?

My current approach is

lua_createtable(L, 0, 2);
int c = lua_gettop(L);
lua_pushstring(L, "a");
lua_pushnumber(L, 4);
lua_settable(L, c);
lua_pushstring(L, "b");
lua_pushnumber(L, 2);
lua_settable(L, c);

to create the inner tables in a loop. Before, this loop, I use

lua_createtable(L, 2, 0);
int outertable = lua_gettop(L);

to create the outer table for 2 numeric slots.

But how can I save the inner tables to the outer table?