The Tetractys of Pythagoras is not a usual, but also not an unknown element of Masonic symbolism. It is sometimes written with numbers (1 – 12 – 123 – 1234), sometimes with the Tetragrammaton, like here.
The image above comes from the Fonds Gaborria, 53th degree “Chevalier. Sublime Philosophe”. Ravignat has the image with his translation of the 64th degree “Chevalier Sublime Philosophe”.
Bibliothèque Numérique Patrimoniale, Fonds Gaborria Ms.-359