login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A334523 Irregular triangle read by rows: row n contains the sequence n, p(n), s(p(n)), p(s(p(n))), p(p(s(p(n)))), s(p(p(s(p(n))))), ..., repeatedy applying (p,s,p) to n, where p = phi (A000010), s = sigma = (A000203), stopping after the first 1 is reached. If 1 is never reached, row n contains n, -1. 4
1, 1, 2, 1, 3, 2, 3, 2, 1, 4, 2, 3, 2, 1, 5, 4, 7, 6, 2, 3, 2, 1, 6, 2, 3, 2, 1, 7, 6, 12, 4, 2, 3, 2, 1, 8, 4, 7, 6, 2, 3, 2, 1, 9, 6, 12, 4, 2, 3, 2, 1, 10, 4, 7, 6, 2, 3, 2, 1, 11, 10, 18, 6, 2, 3, 2, 1, 12, 4, 7, 6, 2, 3, 2, 1, 13, 12, 28, 12, 4, 7, 6, 2, 3, 2, 1, 14, 6, 12, 4, 2, 3, 2, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..94.

L. Alaoglu and P. Erdős, A conjecture in elementary number theory, Bull. Amer. Math. Soc. 50 (1944), 881-882.

EXAMPLE

Triangle begins:

1, 1,

2, 1,

3, 2, 3, 2, 1,

4, 2, 3, 2, 1,

5, 4, 7, 6, 2, 3, 2, 1,

6, 2, 3, 2, 1,

7, 6, 12, 4, 2, 3, 2, 1,

8, 4, 7, 6, 2, 3, 2, 1,

9, 6, 12, 4, 2, 3, 2, 1,

10, 4, 7, 6, 2, 3, 2, 1,

...

For row n=5, for example, we get 5 -> phi(5) = 4 -> sigma(4) = 7 -> phi(7) = 6 -> phi(6) = 2 -> sigma(2) = 3 -> phi(3) = 2 -> phi(2) = 1 (stop).

CROSSREFS

See A032452, A334725 for other versions.

Cf. A000010, A000203, A334685, A334686.

Sequence in context: A026730 A318691 A075256 * A001480 A308117 A270755

Adjacent sequences:  A334520 A334521 A334522 * A334524 A334525 A334526

KEYWORD

nonn,tabf

AUTHOR

N. J. A. Sloane, May 09 2020, following a suggestion from Amiram Eldar.

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 17 19:39 EDT 2021. Contains 343988 sequences. (Running on oeis4.)