Ryantan and pentan

Ryantan and pentan are combination waits, which involve a triplet and an adjacently appended numbered tile. The tile combinations for both appear identical. However, pentan involves terminals, where as ryantan does not.

Pentan is a combination of penchan and tanki. This can occur in two ways, but both involve terminals and tiles 2 or 8. When the triplet is composed of terminals, then the appended tile is either 2 or 8. When the triplet is composed of either 2 or 8 tiles, then the appended tile is either 1 or 9.

Ryantan is a combination of ryanmen and tanki. The tile composition is a converse to pentan. It involves triplets and appended tile of the other numbers: 2 through 8. The terminals are excluded for this combination.