The poetic form of the tetractys is a poem with only five lines. Each line adds another syllable until the last line which has ten as follows: Line 1 – 1 syllable, Line 2 – 2 syllables, Line 3 – 3 syllables, Line 4 – 4 syllables, Line 5 – 10 syllables. This form was discovered thanks to a fellow blogger Annie (see here)
For a more complex form there is the double tetractys, which is similar but has ten lines and is structured as shown below: Line 1 – 1 syllable, Line 2 – 2 syllables, Line 3 – 3 syllables, Line 4 – 4 syllables, Line 5 – 10 syllables, Line 6 – 10 syllables, Line 7 – 4 syllables, Line 8 – 3 syllables, Line 9 – 2 syllables, Line 10 – 1 syllable
Source https://www.youngwriters.co.uk/types-tetractys
You will find here both Tetractys and Double Tetractys as and when I add them and I hope you enjoy them.