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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 (list; graph; refs; listen; history; text; internal format)
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.

LINKS

Table of n, a(n) for n=1..9.

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

Adjacent sequences:  A082868 A082869 A082870 * A082872 A082873 A082874

KEYWORD

nonn

AUTHOR

Cino Hilliard, May 25 2003

EXTENSIONS

Edited and corrected by Farideh Firoozbakht, Jul 07 2009

STATUS

approved

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Last modified May 25 07:56 EDT 2020. Contains 334585 sequences. (Running on oeis4.)