Question: Brihadratha Ikshvaku appears at the beginning of a Sanskrit text that is listed as what number in the Muktika canon?

Context articles: Mundaka Upanishad
Chandogya Upanishad
Maitrayaniya Upanishad
Prashna Upanishad
Kaushitaki Upanishad
Shvetashvatara Upanishad
Brihadratha Ikshvaku
Mantrika Upanishad
Yoga-kundalini Upanishad
Pranagnihotra Upanishad

The Mundaka Upanishad (Sanskrit: मुण्डक उपनिषद् , Muṇḍaka Upaniṣad ) is an ancient Sanskrit Vedic text, embedded inside Atharva Veda.
 It is a Mukhya (primary) Upanishad, and is listed as number 5 in the Muktika canon of 108 Upanishads of Hinduism.
 It is among the most widely translated Upanishads.
The Chandogya Upanishad (Sanskrit: छान्दोग्योपनिषद् , IAST: "Chāndogyopaniṣad") is a Sanskrit text embedded in the Chandogya Brahmana of the Sama Veda of Hinduism.
 It is one of the oldest Upanishads.
 It lists as number 9 in the Muktika canon of 108 Upanishads.
The Maitrayaniya Upanishad (Sanskrit: मैत्रायणीय उपनिषद् , Maitrāyaṇīya Upaniṣad ) is an ancient Sanskrit text that is embedded inside the Yajurveda.
 It is also known as the Maitri Upanishad (Sanskrit: मैत्री उपनिषद् , Maitrī Upaniṣad ), and is listed as number 24 in the Muktika canon of 108 Upanishads.
The Prashna Upanishad (Sanskrit: प्रश्न उपनिषद् , Praśna Upaniṣad ) is an ancient Sanskrit text, embedded inside Atharva Veda, ascribed to "Pippalada" sakha of Vedic scholars.
 It is a Mukhya (primary) Upanishad, and is listed as number 4 in the Muktika canon of 108 Upanishads of Hinduism.
The Kaushitaki Upanishad (Sanskrit: कौषीतकि उपनिषद् , Kauṣītaki Upaniṣad ) is an ancient Sanskrit text contained inside the Rigveda.
 It is associated with the "Kaushitaki" shakha, but a Sāmānya Upanishad, meaning that it is "common" to all schools of Vedanta.
 It was included in Robert Hume's list of 13 Principal Upanishads, and lists as number 25 in the Muktika canon of 108 Upanishads.
The Shvetashvatara Upanishad (Sanskrit:श्वेताश्वतरोपनिशद or श्वेताश्वतर उपनिषद् IAST "Śvetāśvataropaniṣad ") is an ancient Sanskrit text embedded in the Yajurveda.
 It is listed as number 14 in the Muktika canon of 108 Upanishads.
 The Upanishad contains 113 mantras or verses in six chapters.
Brihadratha, belonging to the Ikshvaku race, was a king of the Vedic era (there are several kings of this name in Hindu tradition).
 This name Brihadratha of a warrior king who was a Maharatha is found in the Rig Veda.
 The word, Brihadratha, means the Mighty Warrior.
 He appears at the beginning of the Maitri Upanishad after he had renounced his kingdom in favour of his son, seeking for himself relief from the endless cycle of birth and rebirth.
 No other information about him or his period is available in this text or in any other text.
 Maitri Upanishad belongs to the Maitrayaniya branch of Krishna Yajur Veda, which upanishad was taught to Sakayana by Maitri or Maitreya, the son of Mitra.
 Brihadratha chose the knowledge of the Self when he was offered a boon.
 He gave up his home and possessions and thereafter assisted by Sakayanya even renounced the “I-ness” of his body.
The Mantrika Upanishad (Sanskrit: मन्त्रिक उपनिषत् , IAST:Māntrika Upaniṣad) is a minor Upanishad of Hinduism.
 The Sanskrit text is one of the 22 Samanya Upanishads, is part of the Vedanta and Yoga schools of Hindu philosophy literature, and is one of 19 Upanishads attached to the Shukla Yajurveda.
 In the Muktika canon, narrated by Rama to Hanuman, it is listed at number 32 in the anthology of 108 Upanishads.
The Yoga-kundalini Upanishad (Sanskrit: योगकुण्डलिनी उपनिषत् IAST: Yogakuṇḍalini Upaniṣad ), also called Yogakundali Upanishad (Sanskrit: योगकुण्डल्युपनिषत्, IAST: Yogakuṇḍalī Upaniṣad), is a minor Upanishad of Hinduism.
 The Sanskrit text is one of the 20 Yoga Upanishads, and is one of 32 Upanishads attached to the Krishna Yajurveda.
 In the Muktika canon, narrated by Rama to Hanuman, it is listed at number 86 in the anthology of 108 Upanishads.
The Pranagnihotra Upanishad (Sanskrit: प्राणाग्निहोत्र उपनिषत् , IAST:Pranagnihotra Upaniṣad) is a minor Upanishad of Hinduism.
 In the anthology of 108 Upanishads of the Muktika canon, narrated by Rama to Hanuman, it is listed at number 94.
 The Sanskrit text is one of the 22 Samanya Upanishads, part of the Vedanta school of Hindu philosophy literature and is attached to the Atharva Veda.
 The Upanishad comprises 23 verses.