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Description: The primorial of 4. (Contributed by AV, 28-Aug-2020)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | prmo4 | |- ( #p ` 4 ) = 6 |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | 4nn | |- 4 e. NN |
|
| 2 | prmonn2 | |- ( 4 e. NN -> ( #p ` 4 ) = if ( 4 e. Prime , ( ( #p ` ( 4 - 1 ) ) x. 4 ) , ( #p ` ( 4 - 1 ) ) ) ) |
|
| 3 | 1 2 | ax-mp | |- ( #p ` 4 ) = if ( 4 e. Prime , ( ( #p ` ( 4 - 1 ) ) x. 4 ) , ( #p ` ( 4 - 1 ) ) ) |
| 4 | 4nprm | |- -. 4 e. Prime |
|
| 5 | 4 | iffalsei | |- if ( 4 e. Prime , ( ( #p ` ( 4 - 1 ) ) x. 4 ) , ( #p ` ( 4 - 1 ) ) ) = ( #p ` ( 4 - 1 ) ) |
| 6 | 3 5 | eqtri | |- ( #p ` 4 ) = ( #p ` ( 4 - 1 ) ) |
| 7 | 4m1e3 | |- ( 4 - 1 ) = 3 |
|
| 8 | 7 | fveq2i | |- ( #p ` ( 4 - 1 ) ) = ( #p ` 3 ) |
| 9 | prmo3 | |- ( #p ` 3 ) = 6 |
|
| 10 | 8 9 | eqtri | |- ( #p ` ( 4 - 1 ) ) = 6 |
| 11 | 6 10 | eqtri | |- ( #p ` 4 ) = 6 |