RPL Micro-Challenge: Christmas in July

[Joe Horn]

(07-17-2017 04:54 PM)Jim Horn Wrote:  Great question, Joe! Finite differences quickly gave me the formula; factoring it gave a simplified form (also 4 operations and two single digit constants). Several attempts keep giving me 9 step solutions. Do you have a shorter one? (RPN form used; LBL and RTN not counted)

This is an RPL challenge, but please feel free to implement it for the RPN machine of your choice. I wonder whether the polynomial form or the shorter form would be faster on a machine that doesn't have the secret command that's needed (such as the bare-bones HP-41).

(07-17-2017 09:33 PM)Gerson W. Barbosa Wrote:  Apparently the 20-byte record cannot be broken.

Yes, I'm sure that we're all arriving at the same 20-byte solution.

Final hint to those still hunting: the formula can be expressed this way, which should remind you of a shorter way of expressing it: \(\frac { x(x+1)(x+2) }{ 1\cdot 2\cdot 3 } \)