| Step | 
						Hyp | 
						Ref | 
						Expression | 
					
						
							| 1 | 
							
								
							 | 
							fsumsers.1 | 
							 |-  ( ( ph /\ k e. ( ZZ>= ` M ) ) -> ( F ` k ) = if ( k e. A , B , 0 ) )  | 
						
						
							| 2 | 
							
								
							 | 
							fsumsers.2 | 
							 |-  ( ph -> N e. ( ZZ>= ` M ) )  | 
						
						
							| 3 | 
							
								
							 | 
							fsumsers.3 | 
							 |-  ( ( ph /\ k e. A ) -> B e. CC )  | 
						
						
							| 4 | 
							
								
							 | 
							fsumsers.4 | 
							 |-  ( ph -> A C_ ( M ... N ) )  | 
						
						
							| 5 | 
							
								
							 | 
							eqid | 
							 |-  ( ZZ>= ` M ) = ( ZZ>= ` M )  | 
						
						
							| 6 | 
							
								
							 | 
							eluzel2 | 
							 |-  ( N e. ( ZZ>= ` M ) -> M e. ZZ )  | 
						
						
							| 7 | 
							
								2 6
							 | 
							syl | 
							 |-  ( ph -> M e. ZZ )  | 
						
						
							| 8 | 
							
								
							 | 
							fzssuz | 
							 |-  ( M ... N ) C_ ( ZZ>= ` M )  | 
						
						
							| 9 | 
							
								4 8
							 | 
							sstrdi | 
							 |-  ( ph -> A C_ ( ZZ>= ` M ) )  | 
						
						
							| 10 | 
							
								5 7 9 1 3
							 | 
							zsum | 
							 |-  ( ph -> sum_ k e. A B = ( ~~> ` seq M ( + , F ) ) )  | 
						
						
							| 11 | 
							
								
							 | 
							fclim | 
							 |-  ~~> : dom ~~> --> CC  | 
						
						
							| 12 | 
							
								
							 | 
							ffun | 
							 |-  ( ~~> : dom ~~> --> CC -> Fun ~~> )  | 
						
						
							| 13 | 
							
								11 12
							 | 
							ax-mp | 
							 |-  Fun ~~>  | 
						
						
							| 14 | 
							
								1 2 3 4
							 | 
							fsumcvg2 | 
							 |-  ( ph -> seq M ( + , F ) ~~> ( seq M ( + , F ) ` N ) )  | 
						
						
							| 15 | 
							
								
							 | 
							funbrfv | 
							 |-  ( Fun ~~> -> ( seq M ( + , F ) ~~> ( seq M ( + , F ) ` N ) -> ( ~~> ` seq M ( + , F ) ) = ( seq M ( + , F ) ` N ) ) )  | 
						
						
							| 16 | 
							
								13 14 15
							 | 
							mpsyl | 
							 |-  ( ph -> ( ~~> ` seq M ( + , F ) ) = ( seq M ( + , F ) ` N ) )  | 
						
						
							| 17 | 
							
								10 16
							 | 
							eqtrd | 
							 |-  ( ph -> sum_ k e. A B = ( seq M ( + , F ) ` N ) )  |