Banjo Dmaj7 chord (Open G)D major seventh on the 5-string banjo: 0 2 2 4, and 5 more shapes

Frets, string 4 to string 1: 0 2 2 4 (open position)

1. String 4 (D): open, D
2. String 3 (G): 2nd fret, index finger (barre), A
3. String 2 (B): 2nd fret, index finger (barre), C♯
4. String 1 (D): 4th fret, ring finger, F♯
5. String 5, the short g: open, G, not in the chord

Sounds: D A C♯ F♯  ·  Dmaj7 is D, F♯, A, C♯ (1 · 3 · 5 · 7)

The 5th string: the short g rubs against the F♯ in this shape, a semitone away: some players let it ring, some skip it.

Open G tuning: gDGBD, the short 5th string first, then strings 4 to 1.