From sci.math google group post: "How to generate random number sequences (in your head)"...
With the most relevant answer for you being George Marsaglia's:
~~~~~~~~~~~~~~~~
Choose a 2-digit number, say 23, your "seed".
Form a new 2-digit number:
the 10's digit plus 6 times the units digit.
The example sequence is
23 --> 20 --> 02 --> 12 --> 13 --> 19 --> 55 --> 35 --> ...
and its period is the order of the multiplier, 6, in the group of
residues relatively prime to the modulus, 10. (59 in this case).
The "random digits" are the units digits of the 2-digit numbers,
ie, 3,0,2,2,3,9,5,... the sequence mod 10.
The arithmetic is simple enough to carry out in your head.
This is an example of my "multiply-with-carry"
random number generator, and it seems to provide quite satisfactory
sequences mod 2^32 or 2^64 , particularly well suited to
the way that modern CPU's do integer arithmetic.
edit: so with two people, one of you could chose the seed on alternate days based on some other criteria (like the N you already have or the things @nenadg mentioned (nearby people, cars, windows, cats, dogs, buildings, whatever you agree upon, those things are pretty pseudo-random))
Comments
From sci.math google group post: "How to generate random number sequences (in your head)"...
With the most relevant answer for you being George Marsaglia's:
~~~~~~~~~~~~~~~~
Choose a 2-digit number, say 23, your "seed".
Form a new 2-digit number: the 10's digit plus 6 times the units digit.
The example sequence is 23 --> 20 --> 02 --> 12 --> 13 --> 19 --> 55 --> 35 --> ...
and its period is the order of the multiplier, 6, in the group of residues relatively prime to the modulus, 10. (59 in this case).
The "random digits" are the units digits of the 2-digit numbers, ie, 3,0,2,2,3,9,5,... the sequence mod 10. The arithmetic is simple enough to carry out in your head.
This is an example of my "multiply-with-carry" random number generator, and it seems to provide quite satisfactory sequences mod 2^32 or 2^64 , particularly well suited to the way that modern CPU's do integer arithmetic.
~~~~~~~~~~~~~~~~
source: https://groups.google.com/forum/?hl=en#!msg/sci.math/6BIYd0c...
edit: so with two people, one of you could chose the seed on alternate days based on some other criteria (like the N you already have or the things @nenadg mentioned (nearby people, cars, windows, cats, dogs, buildings, whatever you agree upon, those things are pretty pseudo-random))