K. 1

K. 1 can designate the works of two composers:
# six works of Wolfgang Amadeus Mozart in the original "Köchel Verzeichnis". They appear in manuscript in the Nannerl Notenbuch. Despite being composed in Salzburg between February 1761 and January 1762, they are now considered separate pieces.
# a keyboard sonata by Domenico Scarlatti.

Mozart

#"K. 1a" - Andante in C for Keyboard
#"K. 1b" - Allegro in C for Keyboard
#"K. 1c" - Allegro in F for Keyboard
#"K. 1d" - Minuet in F for Keyboard
#"K. 1e" - Minuet in G for Keyboard
#"K. 1f" - Minuet in C for Keyboard

In the first edition of the "Köchel Verzeichnis" K. 1 referred only to the two minuets in G and C, now designated as K. 1e and K. 1f.

carlatti

The Kirkpatrick numbers for Scarlatti's works are sometimes written with a 'K', sometimes with a 'Kk':
*"K. 1 - Sonata for keyboard