day1-2.prdc

v]{3÷«0Ã}Iv»mŠ .. 14 bytes

{
v]   .. As before.

{    .. "Iterate" the following block:
  3÷ .. integer divide by 3
  «  .. subtract 2
  0Ã .. and take the max with 0.
}
Iv   .. I, Iterate, repeats the above function and collects all resulting
     .. distinct values. v modifies it as before to get "mapbind".
»m   .. Map by taking the tail of each list, so we don't include the original
     .. number.
Š    .. Deeply sum. (In hindsight we ought to be able to save a character here
     .. and just have written »š. Unfortunately š does not sum deeply, even
     .. though Š does.)
};