ruby - Finding the longest collatz sequence for starting numbers < 100

Question

def longest_collatz_sequence(n)
    longest_sequence = []
    (1..n).each do |a|
        sequence = [a]
        until sequence.last == 1
            if a % 2 == 0
                sequence.push(a/2)
            else
                sequence.push(3a + 1)
            end
        end
        if sequence.length > longest_sequence.length
            longest_sequence = sequence
        end
    end
    longest_sequence
end

longest_collatz_sequence(100)

When I run the algorithm, I'm told that there is an unexpected identifier within 3a + 1 and the program doesn't run. Where is my problem?

Thanks!

Answer 1

Make that 3*a, you left out the actual multiplication.