Simple Array Help

I have a custom validation script set up for 20 consecutive form fields.
The fields follow a naming scheme "8_1," "8_2," 8_3," etc...

Once the [Enter] key is pressed (not tab key), it allows this field to jump DOWN to the next field (eg: 8_1 to 8_2 or 8_18 to 8_19. This is, however, different from tabbing over, i set up a different tabbing scheme.

TLDR: how to turn this into an array?

Under "Run Custom Validation Script"

this.getField('8_2').setFocus();
this.getField('8_3').setFocus();
this.getField('8_4').setFocus();
this.getField('8_5').setFocus();
this.getField('8_6').setFocus();
this.getField('8_7').setFocus();
this.getField('8_8').setFocus();
this.getField('8_9').setFocus();
this.getField('8_10').setFocus();
this.getField('8_11').setFocus();
this.getField('8_12').setFocus();
this.getField('8_13').setFocus();
this.getField('8_14').setFocus();
this.getField('8_15').setFocus();
this.getField('8_16').setFocus();
this.getField('8_17').setFocus();
this.getField('8_18').setFocus();
this.getField('8_19').setFocus();
this.getField('8_20').setFocus();

Update:
Each field has one custom validation

Field "8_1" would contain the custom validation script
this.getField('8_2').setFocus();
Field "8_9" would contain the custom validation script
this.getField('8_10).setFocus();
Field "8_19" would contain the custom validation script
this.getField('8_20).setFocus();