Little explorations with HP calculators (no Prime)

[DavidM]

I didn't attempt to apply any symbolic analysis first, as my limited "toolbox" in that regard didn't offer any obvious hints.

Seeing the problem description did, though. So I came up with the following code to produce the numeric result:

Code:












\<<
   WHILE
      DUP SIZE 1. >
   REPEAT
      2 { * } DOSUBS
   END
   EVAL
\>>

The code assumes the initial list is already on the stack before execution. Although I didn't look at the other solutions before putting this together, it does bear a striking resemblance to Thomas' approach.