Compare table values problem

[Ancores]

I have a table like this:

{
	1000, 5000, 3000, 1000, 4000,  -- The numbers are different everytime the script runs.
	5000, 1000, 3000, 5000, 1000,
	5000, 5000, 1000, 4000, 2000
}

If [1], [4] and [7] has the same value I want to add +1 to variable something
and if [1], [4], [7] and [10] has the same value I want to add +1 to variable something again
and if [1], [4], [7], [10] and [13] has the same value I want to add +1 to variable something again.

The only way I can come up with to do this is:

	if(table[1] == table[4] and table[1] == table[7]) then
		something = something+1
	end
	if(table[1] == table[4] and table[1] == table[7] and table[1] == table[10]) then
		something = something+1
	end
	if...

But I need a way to do this in the same if/for or whatever, I guess this is simple but I just can't lol.

Something like:

for i = 1, 5 do
	if(...) then
		something = something + 1
	end
end

Idk