2derangements
Public  01/16/15  10xp  Programming  28.0% 
A derangement is a well known kind of permutation with no fixed point.
Define a 2derangement as a pair P1, P2 of derangements where:
P1[i] != P2[i] for all i
Here are 2 examples of 2derangements for 5 elements:
As the answer is a BIG number, use the following condensed representation:
First 10 digits[number of remaining digits]Last 10 digits
For instance, for 2^127, the representation is:
1701411834[19]5884105728
[My timing: 40 sec]
Define a 2derangement as a pair P1, P2 of derangements where:
P1[i] != P2[i] for all i
Here are 2 examples of 2derangements for 5 elements:
2 4 5 3 1 4 5 1 2 3 4 5 1 2 3 2 4 5 3 1How many 2derangements are there for 208 elements?
As the answer is a BIG number, use the following condensed representation:
First 10 digits[number of remaining digits]Last 10 digits
For instance, for 2^127, the representation is:
1701411834[19]5884105728
[My timing: 40 sec]
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