##AWK BASH: 66 86 63 bytes##
Why didn't I think to this first... :o)
That's 26 less bytes than with AWK, for the same result
a=C3z;echo "X:1
K:A
CzCz$a$a$a3$a$a$a$a$a3Cz$a$a$a$a3CzCzCzCzC"
Like the previous version in AWK, it write on stdout a valid "ABC" notation file (thanks Tobia for finding out that the "L" statement was optional)
It looks like this:
And it sounds exactly like the previous version.
Previous version in AWK (86 Bytes)
Here is a new version; a little longer, but with a more accurate timing. I let the first version bellow for comparison/reference:
BEGIN{a="C3z";print"X:1\nK:A\nL:1/8\nCzCz"a a a"3"a a a a a"3Cz"a a a a"3CzCzCzCzCz";}
This is still a valid "abc" file, which looks like this:
Here is the new midi file (I accelerated the tempo to stay under the 30 seconds limit).
First version in AWK (66 Bytes):##
This is a lot less interesting than my previous answer, but it is a lot shorter, so:
BEGIN{print"X:1\nK:A\nL:1/4\nCCC2C2C2zC2C2C2C2C2zCC2C2C2C2zCCCCC"}
This outputs a valid "abc" file, which can be read into (among others) EasyABC.
It will look like this:
and it will sound like this (midi file). +