Triangular number AND sum of first m factorials

[Gerson W. Barbosa]

(01-11-2018 10:21 AM)Paul Dale Wrote:  Don't let my proof stop your hunt, you'll be able to wile away many hours looking...

At least I can do it a little more efficiently now :-)


100

« { } SWAP 0 1 ROT 1 SWAP
  FOR m m * SWAP OVER + ROT 
     OVER 8 * 1 + ZSqrt 
      { 1 - 2 / + m I→R + } 
      { DROP } 
     IFTE 
     SWAP ROT
  NEXT 
  DROP2 
»

EVAL

-->    { 1 1. 2 2. 17 5. } (about 17 seconds on the real 50g)

ZSqrt from the LongFloat Library

Yes, that's a consequence of the ever growing number of trailing zeros in factorials and the properties of perfect squares.


Gerson.