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Triangular number AND sum of first m factorials
01-11-2018, 06:29 PM (This post was last modified: 01-11-2018 06:31 PM by Gerson W. Barbosa.)
Post: #13
RE: Triangular number AND sum of first m factorials
(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.
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RE: Triangular number AND sum of first m factorials - Gerson W. Barbosa - 01-11-2018 06:29 PM



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