Is a BIBD even possible?

We saw in the video that it's possible a BIBD doesn't exist at all. It's useful to calculate the lambda beforehand, and if the result isn't an integer, there isn't a possible BIBD.

Don't bust out the pen and paper yet: the lambda() function has been defined for you. It takes as input t = number of treatments, k = number of treatments per block, and r = number of repetitions. It then calculates lambda according to this formula: r(k - 1) / (t - 1).

Try the different combinations of t, k, and r using lambda() in your console, and choose the answer which does NOT have a BIBD.