by neufer » Mon Jun 17, 2019 12:52 pm
https://en.wikipedia.org/wiki/El_Castillo,_Chichen_Itza wrote:
<<The pyramid consists of a series of square terraces with stairways up each of the four sides to the temple on top. Sculptures of plumed serpents run down the sides of the northern balustrade. Around the spring and autumn equinoxes, the late afternoon sun strikes off the northwest corner of the pyramid and casts a series of triangular shadows against the northwest balustrade, creating the illusion of a feathered serpent "crawling" down the pyramid. The event has been very popular and is witnessed by thousands of visitors at the spring equinox, but it is questionable whether it is a result of a purposeful design, because the light-and-shadow effect can be observed, without major changes, during several weeks around the equinoxes. Each of the pyramid's four sides has around 91 steps which, when added together and including the temple platform on top as the final "step",may produce a total of 365 steps (the steps on the south side of the pyramid are eroded) (which is equal to the number of days of the Haab' year).>>
https://en.wikipedia.org/wiki/Square_pyramidal_number wrote:
<<In mathematics, a pyramid number, or square pyramidal number, is a figurate number that represents the number of stacked spheres in a pyramid with a square base. Square pyramidal numbers also solve the problem of counting the number of squares in an n × n grid.
1, 5, 14, 30, 55, 91, 140, 204, 285, 385, 506, 650, 819, ... (sequence A000330 in the OEIS).>>
[quote="https://en.wikipedia.org/wiki/El_Castillo,_Chichen_Itza"]
[float=left][img3="The serpent effect demonstrated during the night show with artificial lighting."]https://upload.wikimedia.org/wikipedia/commons/thumb/9/93/Chichen-Itza-Serpent-Effect.jpg/800px-Chichen-Itza-Serpent-Effect.jpg[/img3][/float]
<<The pyramid consists of a series of square terraces with stairways up each of the four sides to the temple on top. Sculptures of plumed serpents run down the sides of the northern balustrade. Around the spring and autumn equinoxes, the late afternoon sun strikes off the northwest corner of the pyramid and casts a series of triangular shadows against the northwest balustrade, creating the illusion of a feathered serpent "crawling" down the pyramid. The event has been very popular and is witnessed by thousands of visitors at the spring equinox, but it is questionable whether it is a result of a purposeful design, because the light-and-shadow effect can be observed, without major changes, during several weeks around the equinoxes. Each of the pyramid's four sides has around 91 steps which, when added together and including the temple platform on top as the final "step",may produce a total of 365 steps (the steps on the south side of the pyramid are eroded) (which is equal to the number of days of the Haab' year).>>[/quote][quote="https://en.wikipedia.org/wiki/The_Deck_of_Cards"]
<<To come up with 365 spots on a deck of cards, one would have to assume that the face cards have 11, 12 and 13 spots respectively, plus assume exactly one joker with one spot.>>[/quote][quote="https://en.wikipedia.org/wiki/Square_pyramidal_number"]
[float=left][img3=""]https://upload.wikimedia.org/wikipedia/commons/thumb/b/b7/Mus%C3%A9e_historique_de_Strasbourg-Boulets_en_pierre.jpg/330px-Mus%C3%A9e_historique_de_Strasbourg-Boulets_en_pierre.jpg[/img3][/float]<<In mathematics, a pyramid number, or square pyramidal number, is a figurate number that represents the number of stacked spheres in a pyramid with a square base. Square pyramidal numbers also solve the problem of counting the number of squares in an n × n grid.
[b]1, 5, 14, 30, 55, [color=#FF0000]91[/color], 140, 204, 285, 385, 506, 650, 819, ... [/b](sequence A000330 in the OEIS).>>[/quote]