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 A199426 Janet helicoidal classification of the periodic table. 1
 1, 2, 3, 4, 5, 6, 7, 10, 9, 8, 11, 12, 13, 14, 15, 18, 17, 16, 19, 20, 21, 22, 23, 24, 25, 30, 29, 28, 27, 26, 31, 32, 33, 36, 35, 34, 37, 38, 39, 40, 41, 42, 43, 48, 47, 46, 45, 44, 49, 50, 51, 54, 53, 52, 55, 56, 57, 58, 59, 60, 61, 62, 63, 70, 69, 68, 67, 66, 65, 64 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS A permutation of the natural numbers up to 120 (Janet table; in OEIS Wiki, Periodic table). Or more (extension). Janet explicitly published his table in reference (1), leaflet 7. This was a consequence of his helicoidal classification of the periodic table created with four tangential increasing cylinders on which the numbers are written (2), leaflet 3, (for the first 3 cylinders): (A)                            25 26             43 44                                24 27             42 45         7  8       15 16       23 28 33 34       41 46 51 52         6  9       14 17       22 29 32 35       40 47 50 53 1 2 3 4 5 10 11 12 13 18 19 20 21 30 31 36 37 38 39 48 49 54 55 56. A boustrophedon path is used. 1 increases, 2 decreases. a(n) is the vertical terms taken from bottom to top. By 2 consecutive verticals the numbers of the terms are 2,2,6,2,6,2,10,6,2,... = A167268. REFERENCES (1) Charles Janet, Essais de classification hélicoidale des éléments chimiques, avril 1928, N 3, Beauvais, 2+104 pages, 4 leaflets (3 to 7). (2) Charles Janet, La classification hélicoidale des éléments chimiques, novembre 1928, N 4, Beauvais, 2+80 pages, 10 leaflets. LINKS FORMULA A167268/2 = 1,1,3,1,3,1,5,3,1,5,3,1,... = b(n). b(n) repeated is every term of A167268 shared in 2 equal parts: 1,1,1,1,3,3,1,1,5,5,3,3,1,1,... = c(n), distribution of verticals of (A). a(n) is created by mixed increasing 1, 3,  5,6,7, 11, 13,14,15,   via b(n) (or both via c(n)) and                                 2, 4, 10,9,8, 12, 18,17,16, (separately decreasing from right to left for 2, 4, 8,9,10, 11, 16,17,18). CROSSREFS Sequence in context: A194963 A072794 A181820 * A119257 A266645 A266646 Adjacent sequences:  A199423 A199424 A199425 * A199427 A199428 A199429 KEYWORD nonn AUTHOR Paul Curtz, Nov 06 2011 STATUS approved

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Last modified January 16 05:52 EST 2021. Contains 340195 sequences. (Running on oeis4.)