512
( a 2 + b 2 + c 2 + d 2 ) = ( b 2 + c 2 + d 2 ) + ( a 2 )
123
( a 2 + b 2 ) = ( a 2 ) + ( b 2 )
235
( b 2 + c 2 + d 2 ) = ( b 2 ) + ( c 2 + d 2 )
351
( a 2 + b 2 + c 2 + d 2 ) = ( a 2 + b 2 ) + ( c 2 + d 2 )