English Gothic architecture Exeter Cathedral is built in this style, as is the crossing of Ely Cathedral, (including the famous octagonal lantern, built between 1322 and 1328 to replace the fallen central tower), three west bays of the choir and the Lady Chapel. In Scotland, Melrose Abbey was a noteworthy example, though much of it is now in ruins. The Perpendicular Gothic period (or simply Perpendicular) is the third historical division of English Gothic architecture, and is so-called because it is characterised by an emphasis on vertical lines. An alternative name, the Rectilinear, was suggested by Edmund Sharpe, and is preferred by some
Octagonal number pronic number. Octagonal numbers consistently alternate parity. Octagonal numbers are occasionally referred to as "star numbers," though that term is more commonly used to refer to centered dodecagonal numbers. Solving the formula for the "n"-th octagonal number, formula_2 for "n" gives An arbitrary number "x" can be checked for octagonality by putting it in this equation. If "n" is an integer, then "x" is the "n"-th octagonal number. If "n" is not an integer, then "x" is not octagonal. Octagonal number An octagonal number is a figurate number that represents an octagon. The octagonal number for "n" is given by