Yeti

Is there really no simpler way to drop the top of stack that works for strings and numbers and in all versions of Dc?

 

{{works with|Python|2.x}}

This is a sequentialised variant of the well known sieve method (ab)using a dictionary as sparse array.

Alternatively you can describe it as finding the wheels and moving them on a tape. The only knowledge is to start looking 2 instead of starting with 1, but the original sieve does skip 1 too. 2 is not hard coded to be prime. The algorithm detects it as 1st prime and then puts the 2-wheel on the tape.

 

 

<lang python>L = {}

...the program has to be terminated by the user e.g. by typing ctrl-c.

 

{{works with|Python|2.x}}

n = 2

 

if n in L:

P = L[n]

else:

P = n