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 A328719 Triangular array read by rows: row n consists of the numbers k from 1 to n sorted in ascending lexicographic order of their sequences of p-adic valuations. 1
 1, 1, 2, 1, 3, 2, 1, 3, 2, 4, 1, 5, 3, 2, 4, 1, 5, 3, 2, 6, 4, 1, 7, 5, 3, 2, 6, 4, 1, 7, 5, 3, 2, 6, 4, 8, 1, 7, 5, 3, 9, 2, 6, 4, 8, 1, 7, 5, 3, 9, 2, 10, 6, 4, 8, 1, 11, 7, 5, 3, 9, 2, 10, 6, 4, 8, 1, 11, 7, 5, 3, 9, 2, 10, 6, 4, 12, 8, 1, 13, 11, 7, 5, 3, 9, 2, 10, 6, 4, 12, 8, 1, 13, 11, 7, 5, 3, 9, 2, 14, 10, 6, 4, 12, 8 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS EXAMPLE 12 = 2^2 * 3 can be viewed as a sequence (2, 1, 0, 0, ...) of p-adic valuations, and 20 = 2^2 * 5 as (2, 0, 1, 0, ...); (2, 0, 1, 0, ...) comes before (2, 1, 0, 0, ...) in lexicographic order, so 20 "<" 12 from that perspective. The triangle begins:   1,   1,  2,   1,  3,  2,   1,  3,  2,  4,   1,  5,  3,  2,  4,   1,  5,  3,  2,  6,  4,   1,  7,  5,  3,  2,  6,  4,   1,  7,  5,  3,  2,  6,  4,  8,   1,  7,  5,  3,  9,  2,  6,  4,  8,   1,  7,  5,  3,  9,  2, 10,  6,  4,  8,   1, 11,  7,  5,  3,  9,  2, 10,  6,  4,  8,   1, 11,  7,  5,  3,  9,  2, 10,  6,  4, 12,  8,   1, 13, 11,  7,  5,  3,  9,  2, 10,  6,  4, 12,  8,   1, 13, 11,  7,  5,  3,  9,  2, 14, 10,  6,  4, 12,  8,   1, 13, 11,  7,  5,  3, 15,  9,  2, 14, 10,  6,  4, 12,  8,   1, 13, 11,  7,  5,  3, 15,  9,  2, 14, 10,  6,  4, 12,  8, 16,   1, 17, 13, 11,  7,  5,  3, 15,  9,  2, 14, 10,  6,  4, 12,  8, 16,   1, 17, 13, 11,  7,  5,  3, 15,  9,  2, 14, 10,  6, 18,  4, 12,  8, 16,   1, 19, 17, 13, 11,  7,  5,  3, 15,  9,  2, 14, 10,  6, 18,  4, 12,  8, 16,   1, 19, 17, 13, 11,  7,  5,  3, 15,  9,  2, 14, 10,  6, 18,  4, 20, 12,  8, 16, PROG (PARI) L=List(); n=1; while(n<=20, i=1; while(i

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Last modified August 13 05:41 EDT 2020. Contains 336442 sequences. (Running on oeis4.)