17 x 23 = 391

  Jarasandha attacked Mathura with an army of 23 Akshohinis. His allies were 

1. Shishupala (Chedi), 
2. Bhagadatta (son of Narakasura of Pragjyotisha), 
3. Rukmi (Vidarbha), 
4. Vinda-Anuvinda (Avanti), 
5. Paundraka (Pundra), 
6. Dantavakra (Karusha), and others. 

But Krishna and Balarama easily destroyed the whole army, except for Jarasandha and his allies. A humiliated Jarasandha attacked Mathura 17 times but was repeatedly defeated.

18th Time On arrival of Kalayavana shifted to Dwarka

https://harekrishnainfo.blogspot.com/search/label/KamsaJarasandhaKalayavana