केतु (Ketu) पूजा -

For the pacification (shanti) of the planet Ketu, different types of chanting (jaap) are recommended in Vedic tradition, with varying counts depending on the specific method.
The most common counts are 17,000 or 18,000 repetitions of the Beej (seed) mantra, which in the Kali Yuga is sometimes multiplied by four, resulting in 68,000 recitations.

Ketu Beej (Seed) Mantra -
Om Sraam Sreem Sraum Sah Ketave Namah
(ॐ स्रां स्रीं स्रौं सः केतवे नमः॥)

Ketu Gayatri Mantra -
Om Chitravarnaya Vidhmahe Sarparoopaya Dhimahi Tanno Ketu Prachodayat
(ॐ चित्रवर्णाय विद्महे सर्परूपाय धीमहि तन्नो केतु प्रचोदयात्॥)