I manually evaluate this cell to set Prime[0]

Prime[0] = 1

I manually evaluate this cell to reset Prime[0]

Prime[0] =.

In case I forget to do it, is there a way to automatically evaluate the second cell when I close the nb?


I'm working with bags of primes and want to use $p_0$ as the bag for all prime greater than the square-root of some $n$.

Displayed as: $\left\{p_0^1,p_1^5,p_2^2,p_3^1,p_4^1\right\}$

With counts as: $\left\{1,5,2,1,1\right\}$

  • 1
    $\begingroup$ Have you seen NotebookEventActions[]? $\endgroup$ Sep 3, 2012 at 7:03
  • 5
    $\begingroup$ You also could just define something like: prime[x_Integer /; x >= 0] := If[x == 0, 1, Prime[x]] as another approach. $\endgroup$ Sep 3, 2012 at 7:07
  • $\begingroup$ @J.M.-- Looks interesting. I determined that if I exit mma, the change gets reset automatically. It's only a problem when I open or create nbs from the current session. Thanks. $\endgroup$ Sep 3, 2012 at 7:54
  • 2
    $\begingroup$ I was hoping you'd answer your question yourself, since you figured out how to use it... :) $\endgroup$ Sep 3, 2012 at 12:25

1 Answer 1


Per J.M., I did this and it works. I put it in the same cell as the setup.

SetOptions[SelectedNotebook[],NotebookEventActions ->
Quiet[{Unprotect[Prime]; Prime[0] =.; Protect[Prime];}]}];
{Unprotect[Prime]; Prime[0] = 1; Protect[Prime]};    

Edited to add the Quiet to the actions.


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