From Elie Joncourt’s “De Natura Et Prae Claro Usu Simplicissimae Specie Numerorum Trigonalium” – a list of the first 20k “triangular numbers“.  Essentially a useless task, since n triangular number can be derived from (n*(n+1))/2, I really enjoy the intensity and nearly material physicality that this lends otherwise immaterial numbers. Download the full facsimile (fantastic … Continue reading 20k Triangular Numbers