The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A361970 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A361970

a(n) is the least number k such that the equation uphi(x) = k has exactly n solutions, or -1 if no such k exists, where uphi is the unitary totient function (A047994).
(history; published version)

#13 by N. J. A. Sloane at Sun Apr 02 08:27:28 EDT 2023

STATUS

reviewed

approved

#12 by Vaclav Kotesovec at Sun Apr 02 06:15:40 EDT 2023

STATUS

proposed

reviewed

#11 by Amiram Eldar at Sun Apr 02 06:06:48 EDT 2023

STATUS

editing

proposed

#10 by Amiram Eldar at Sun Apr 02 06:06:35 EDT 2023

COMMENTS

Is there any n for which a(n) = -1?

STATUS

proposed

editing

Discussion

Sun Apr 02

06:06

Amiram Eldar: OK, added.

#9 by Amiram Eldar at Sun Apr 02 04:35:39 EDT 2023

STATUS

editing

proposed

Discussion

Sun Apr 02

05:53

Vaclav Kotesovec: A good comment here would be if there is any n for which a(n)=-1 ?

#8 by Amiram Eldar at Sun Apr 02 04:35:17 EDT 2023

LINKS

Amiram Eldar, <a href="/A361970/b361970.txt">Table of n, a(n) for n = 0..300</a>

STATUS

approved

editing

#7 by N. J. A. Sloane at Sat Apr 01 22:06:47 EDT 2023

STATUS

proposed

approved

#6 by Amiram Eldar at Sat Apr 01 05:29:45 EDT 2023

STATUS

editing

proposed

#5 by Amiram Eldar at Sat Apr 01 05:27:14 EDT 2023

CROSSREFS

Cf. A047994, A135347, A347771, A361966, A361967, A361968, A361969, A361971.

STATUS

proposed

editing

#4 by Amiram Eldar at Sat Apr 01 04:03:39 EDT 2023

STATUS

editing

proposed