A260589 Irregular table read by rows: n-th row lists the prime factors of A173426(n), with repetition.

11, 11, 3, 3, 37, 37, 11, 11, 101, 101, 41, 41, 271, 271, 3, 3, 7, 7, 11, 11, 13, 13, 37, 37, 239, 239, 4649, 4649, 11, 11, 73, 73, 101, 101, 137, 137, 3, 3, 3, 3, 37, 37, 333667, 333667, 12345678910987654321, 7, 17636684157301569664903, 3, 3, 7, 7, 2799473675762179389994681, 1109, 4729

Offset: 1

Author

M. F. Hasler, Jul 29 2015

Keywords

• nonn
• tabf
• base

Comments

Row lengths are given by A260588(n). In particular, row n = 1 would have length 0, i.e., no element, because A173426(1) = 1 has no prime factors. Therefore the sequence can be considered to start with row n = 2. (The offset refers to the k-th element of the "flattened" sequence.)

For n = 1 through n = 9, A173426(n) is the square of the repunit 1...1 of length n, therefore every prime factor appears twice. This is no longer the case for n > 9.

Links

• M. F. Hasler, Table of k, a(k) for k = 1..150 (Rows n = 2 through 30, flattened.)
• M. F. Hasler, Factorization of A173426 = 123...321, OEIS wiki, July 2015.

Crossrefs

Cf. A001222, A075023, A075024, A173426, A260587, A260588.

Programs

PARI

A260589_row(n)=A027746_row(A173426(n))

PARI

vector(30,n,A027746_row(A173426(n))) \\ You may concat() this.

Formula

n | A173426(n) | factors = n-th row of this table

1 | 1 | []

2 | 121 | [11, 11]

3 | 12321 | [3, 3, 37, 37]

4 | 1234321 | [11, 11, 101, 101]

5 | 123454321 | [41, 41, 271, 271]

6 | 12345654321 | [3, 3, 7, 7, 11, 11, 13, 13, 37, 37]