(49G) Friday 13th calculation

[Joe Horn]

Here's my ancient User RPL version, which was included in "One-Minute Marvels" by Richard Nelson and Wlodek Mier-Jedrzejowicz:

Code:

<<  1000000  /  1.13  +  13  FOR  d  6.133  d  DDAYS  7  MOD  NOT  d  IFT  NEXT  >>

Since there are not many ways of doing it, the code looks very much like yours.

Same input as yours: Just the desired year. However, my version assumes MDY mode. Changing it to DMY is left as an exercise for the student.