Eu acho que isso é apenas
row_number()
e agregação:select listagg(row_number, ',') within group (order by row_number) as row_numbers,
loan_id, txn_entry_api_name, sum(txn_amt) as txn_amt,
listagg(txn_entry_api_name, ',') within group (order by row_number) as txn_entry_api_name
from (select t.*,
row_number() over (partition by loan_id, txn_entry_api_name, abs(txn_amt) order by row_number) as seqnum
from t
) t
group by seqnum;