After such a lengthened ā of the reduplicate there is added the augment nuṭ (n) to the short a of the root which ends in a double consonant.,
As from अञ्च्-आ अञ्च् = आन् अञ्च्, which with the affixes of the Perfect gives us, आनङ्ग, आनङ्गतुः, आनङ्गुः ॥ From अञ्ज्-आनञ्ज, आनञ्जतुः, आनञ्जुः ॥ Why do we say 'containing two consonants'? Observe आट, आटतुः, आटुः ॥
With regard to नुट् augment, ऋ is considered like र्, as आनृधतुः, आनृधुः ॥ This proceeds on a vartika to be found under the Pratyahara sutra ऐ औच् ॥ The vartika is नुड्विधि-लादेश-विनामाषु ऋकारे प्रतिविधातव्यम् ॥ The examples of लादेश are क्लृप्तः, क्लृप्तवान्; (See 8.2.18) and of विनाम are कर्तॄणाम् and भर्तॄणाम् ॥,