Palatal nasal in various encoding schemes
ITRANS: ~n, JNa
Harvard Kyoto: J
Velthius: ~n
Unicode: ñ, ञ, ཉ
I have seen nya but I'm not sure what system this comes from. Ñāṇatiloka spells his name Nyanatiloka for instance.
N is typically used for the retroflex nasal.
ITRANS: N
Harvard Kyoto: N
Velthius: .n
Unicode: ṇ, ण, ཎ
नमस्ते
Jayarava