1400, 1706, 1949, 1958, 1961, 1973, 1983, 1987, 1989, 1997, 1999, 2002, 2011 The Nth term is the year when pi was first calcuated to 10^N decimal places. 2011 is the 13th term because pi was calculated to ten trillion (10^13) places that year. Pi has not yet been calculated to 10^14 places. Since 1949, the average time for each new factor of ten has been 6.2 years, a doubling every 1.9 years. I think it's a good illustration of the remarkable progress in computer hardware and software. If this trend continues, one mole (Avogadro's number) of digits will be known before the 2080s. I submitted it to OEIS, with references, but it was ruled "inappropriate." I considered adding a zeroth term, -250, the approximate year when Archimedes first calculated pi. Others had *measured* pi to more than one decimal place long before his time, but he was the first person known to have *calculated* it.