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.

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

Offset

1,2

Comments

Row lengths are A288636(n). - Gus Wiseman, Jun 12 2017

Links

N. J. A. Sloane, Table of n, a(n) for n = 1..20181

N. J. A. Sloane, Maple programs for A007916, A278028, A278029, A052409, A089723, A277564

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.

Cf. A007916, A089723, A277562, A288636.

Sequence in context: A307277 A210691 A262175 * A124424 A057044 A153899

Adjacent sequences: A278025 A278026 A278027 * A278029 A278030 A278031

Keyword

nonn,tabf

Author

N. J. A. Sloane, Nov 09 2016

Status

approved