[seqfan] sums of signed squares

Brendan McKay bdm at cs.anu.edu.au
Tue Mar 10 10:32:34 CET 2009


Another problem from the Mathematics help desk at Wikipedia:

How many ways to write 0 as a sum
  +- 1^2 +- 2^2 +- 3^2 +- ... +- n^2 ?
Here "+-" is "plus or minus".

Seems to be 0 for n <= 6, then starting at n=7:
   2,2,0,0,2,10,0,0,86,114,...

Brendan.




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