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A082871
First component x of pairs (x,y) where x <= y and x!+y! is a square, sorted on x.
1
0, 0, 0, 1, 1, 1, 1, 2, 4
OFFSET
1,8
COMMENTS
Conjecture: the only solutions for x!+y!=n^2 (x <= y) are x=0,0,0,1,1,1,2,4 and y=4,5,7,4,5,7,2,5 respectively.
PROG
(PARI) sumfactsq(n) = { for(x=0, n, for(y=1, n, z = x!+y!; if(issquare(z), print1(x" ")) ) ) }
CROSSREFS
Cf. A151819.
Sequence in context: A176649 A216979 A334822 * A321406 A166926 A266296
KEYWORD
nonn
AUTHOR
Cino Hilliard, May 25 2003
EXTENSIONS
Edited and corrected by Farideh Firoozbakht, Jul 07 2009
STATUS
approved