The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A007372

(Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
Showing entries 1-10 | older changes

A007372

Numbers k such that sigma(x) = k has exactly 3 solutions.
(history; published version)

#36 by OEIS Server at Mon Nov 18 04:35:43 EST 2024

LINKS

Amiram Eldar, <a href="/A007372/b007372_1.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..1000 from Donovan Johnson)

#35 by Alois P. Heinz at Mon Nov 18 04:35:43 EST 2024

STATUS

reviewed

approved

Discussion

Mon Nov 18

04:35

OEIS Server: Installed new b-file as b007372.txt.  Old b-file is now b007372_1.txt.

#34 by Stefano Spezia at Mon Nov 18 00:59:54 EST 2024

STATUS

proposed

reviewed

#33 by Stefano Spezia at Mon Nov 18 00:59:51 EST 2024

STATUS

editing

proposed

#32 by Stefano Spezia at Mon Nov 18 00:59:48 EST 2024

LINKS

Robert G. Wilson, V, v, <a href="/A007015/a007015.pdf">Letter to N. J. A. Sloane, Jul. 1992</a>.

STATUS

proposed

editing

#31 by Amiram Eldar at Mon Nov 18 00:29:13 EST 2024

STATUS

editing

proposed

#30 by Amiram Eldar at Sun Nov 17 23:57:16 EST 2024

LINKS

Robert G. Wilson, V, <a href="/A007015/a007015.pdf">Letter to N. J. A. Sloane, Jul. 1992</a>.

#29 by Amiram Eldar at Sun Nov 17 23:53:32 EST 2024

CROSSREFS

Cf. A007369, A007370, A007371, etc.

Cf. A000203.

Number of solutions: A007369 (0), A007370 (1), A007371 (2), this sequence (3), A060660 (4), A060661 (5), A060662 (6), A060663 (7), A060664 (8), A060665 (9), A060666 (10), A060678 (11), A060676 (12).

#28 by Amiram Eldar at Sun Nov 17 23:52:56 EST 2024

LINKS

Max Alekseyev, <a href="https://oeis.org/wiki/User:Max_Alekseyev/gpscripts">PARI/GP Scripts for Miscellaneous Math Problems</a> (invphi.gp).

R. Robert G. Wilson, V, <a href="/A007015/a007015.pdf">Letter to N. J. A. Sloane, Jul. 1992</a>

#27 by Amiram Eldar at Sun Nov 17 23:52:38 EST 2024

LINKS

Amiram Eldar, <a href="/A007372/b007372_1.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..1000 from Donovan Johnson)

Max Alekseyev, <a href="https://oeis.org/wiki/User:Max_Alekseyev/gpscripts">PARI/GP Scripts for Miscellaneous Math Problems</a> (invphi.gp).

PROG

(PARI) is(k) = invsigmaNum(k) == 3 \\ Amiram Eldar, Nov 17 2024, using Max Alekseyev's invphi.gp