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A278028 Let {c(i)} = A007916 denote the sequence of numbers > 1 which are not perfect powers. Every positive integer n has a unique representation as a tower n = c(x_1)^c(x_2)^c(x_3)^...^c(x_k), where the exponents are nested from the right. The sequence is an irregular triangle read by rows, where the n-th row lists x_1, ..., x_k. 15
1, 2, 1, 1, 3, 4, 5, 1, 2, 2, 1, 6, 7, 8, 9, 10, 11, 1, 1, 1, 12, 13, 14, 15, 16, 17, 18, 19, 3, 1, 20, 2, 2, 21, 22, 23, 24, 1, 3, 25, 26, 27, 4, 1, 28, 29, 30, 31 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
Row lengths are A288636(n). - Gus Wiseman, Jun 12 2017
LINKS
EXAMPLE
Rows 2 through 32 are:
1,
2,
1, 1,
3,
4,
5,
1, 2,
2, 1,
6,
7,
8,
9,
10,
11,
1, 1, 1,
12,
13,
14,
15,
16,
17,
18,
19,
3, 1,
20,
2, 2,
21,
22,
23,
24,
1, 3,
...
CROSSREFS
See A277564 for another version.
Sequence in context: A307277 A210691 A262175 * A124424 A057044 A372760
KEYWORD
nonn,tabf
AUTHOR
N. J. A. Sloane, Nov 09 2016
STATUS
approved

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Last modified July 20 05:10 EDT 2024. Contains 374441 sequences. (Running on oeis4.)