e_rows = (10,34)
e_col = (4,6,8,10,13,15,17,19)
inst = 'A'

test_list = [inst+'_r'+str(e_rows[0])+'c'+str(i) for i in range(4,12,2)]
test_list.extend([inst+'_r'+str(e_rows[0])+'c'+str(i) for i in range(13,21,2)])
test_list.extend([inst+'_r'+str(e_rows[1])+'c'+str(i) for i in range(4,12,2)])
test_list.extend([inst+'_r'+str(e_rows[1])+'c'+str(i) for i in range(13,21,2)])

print(test_list)

['A_r10c4', 'A_r10c6', 'A_r10c8', 'A_r10c10', 'A_r10c13', 'A_r10c15', 'A_r10c17', 'A_r10c19', 'A_r34c4', 'A_r34c6', 'A_r34c8', 'A_r34c10', 'A_r34c13', 'A_r34c15', 'A_r34c17', 'A_r34c19']