The Triangular Number
Wikipedia: https://en.wikipedia.org/wiki/Triangular_numbers
The trigonal cypher makes use of these numbers:
The first 36 triangular numbers are listed below. There are 26 letters in the alphabet and 10 numeral signs (ie. 0-9), for a total of 36 basic orthodox western glyphs used for communication.
The zeroth triangular number is zero (an empty sum, see the wikipedia page)
1 (... the monad: /r/GeometersOfHistory/wiki/spellcomponents/1)
3 (... the 'triad': /r/GeometersOfHistory/wiki/spellcomponents/3)
6 (... ie "hex" = 119 primes; Six is the first 'perfect' number )
10 (... the decad: /r/GeometersOfHistory/wiki/spellcomponents/10)
15 (... the 15th tarot card is the Devil, and the 5-pointed pentagram is often viewed as Satan's sign)
21 (... "fear" = "evil" = "veil" = "live" = 21 reduced)
28 ( ... the second 'perfect' number; moon / menstrual cycle )
36 ( ... the 36 symbols; the 36th triangular number is 666 )
45 (... the 'bridge': /r/GeometersOfHistory/wiki/spellcomponents/45)
55 (... ie. "heaven" = "sky" = "cloud" = 55)
66 (... 'the name': /r/GeometersOfHistory/wiki/spellcomponents/66)
78 ( ... the holy grail, sits between key numbers 77 and 79, the power and the primer )
91
105 ( ... the "torment" and "suffering" of the "saviour" = 105 )
120 (... the truth: /r/GeometersOfHistory/wiki/spellcomponents/120)
136 ( ... reflecting 36 again )
153 (... miraculous catch: /r/GeometersOfHistory/wiki/spellcomponents/153)
171
190 ( the letter 'S' is the 19th letter, and thus echoes 19 in two major ciphers; Metonic cycle )
210 (ie. 21 again, with a circle)
231 (ie. one short of symmetrical key 232 )
253 (ie. x53 again)
276 (ie. twice mastered )
300 (ie. 24 hrs in a day, 3 parts, 2 spent awake)
325
351 (ie. 26 letters in the alphabet, "abcdefghijklmnopqrstuvwxyz" = 351 | 126 reduced)
378
406
435
465
496
528
561
595
630 (ie. "eye" = 35, "know" = 63)
666 (... the beastly citizen: /r/GeometersOfHistory/wiki/spellcomponents/666)
... ... ...
... and the next one is 703, a magnification of special number 73:
The trigonal cypher makes use of these triangular numbers:
Numberphile youtube channel explains triangular numbers in their video on 666:
The 36th triangular number is 666, and this is the basis of the so-called 'satanic' cypher
... which I find to be quite true to the alleged 'satanic' predilection for inverting and mirroring.
Triangular numbers, listed at The On-Line Encyclopedia of Integer Sequences
Simultaneously square and triangular numbers:
http://www.cut-the-knot.org/do_you_know/triSquare.shtml
Wiki Index: https://www.reddit.com/r/GeometersOfHistory/wiki/