The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A196677 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A196677

Numbers n such that sum of the divisors of n equals the sum of the reversals of the divisors of n. Numbers with all palindrome divisors are not in the sequence.
(history; published version)

#29 by Charles R Greathouse IV at Thu Sep 08 08:45:59 EDT 2022

PROG

(MAGMAMagma) f:=func<n|Intseq(n) eq Reverse(Intseq(n))>; g:=func<n|[&+Divisors(n)] eq [&+[Seqint(Reverse(Intseq(d))):d in Divisors(n)]]>; [k:k in [1..80000]| g(k) and not forall{d:d in Divisors(k)|f(d)}]; // Marius A. Burtea, Nov 20 2019

Discussion

Thu Sep 08

08:45

OEIS Server: https://oeis.org/edit/global/2944

#28 by OEIS Server at Wed Nov 27 04:46:15 EST 2019

LINKS

Giovanni Resta, <a href="/A196677/b196677_2.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..57 from R. J. Mathar, 58..1000 from Amiram Eldar)

#27 by Giovanni Resta at Wed Nov 27 04:46:15 EST 2019

STATUS

editing

approved

Discussion

Wed Nov 27

04:46

OEIS Server: Installed new b-file as b196677.txt.  Old b-file is now b196677_2.txt.

#26 by Giovanni Resta at Wed Nov 27 04:46:03 EST 2019

LINKS

Amiram Eldar, Giovanni Resta, <a href="/A196677/b196677_2.txt">Table of n, a(n) for n = 1..100010000</a> (terms 1..57 from R. J. Mathar, 58..1000 from Amiram Eldar)

STATUS

approved

editing

#25 by OEIS Server at Wed Nov 20 09:31:57 EST 2019

LINKS

Amiram Eldar, <a href="/A196677/b196677_1.txt">Table of n, a(n) for n = 1..1000</a> (terms 1..57 from R. J. Mathar)

#24 by Susanna Cuyler at Wed Nov 20 09:31:57 EST 2019

STATUS

proposed

approved

Discussion

Wed Nov 20

09:31

OEIS Server: Installed new b-file as b196677.txt.  Old b-file is now b196677_1.txt.

#23 by Marius A. Burtea at Wed Nov 20 07:43:57 EST 2019

STATUS

editing

proposed

#22 by Marius A. Burtea at Wed Nov 20 07:38:40 EST 2019

COMMENTS

The sequence contains the terms palindromic numbers: 989, 97079, 98789, 99299, 1226221, 1794971, 13488431,…. Divisors (97079) = {1, 193, 503, 97079} and 193 + 503 = 696 = 391 + 305. Divisors (1794971) = {1, 1031, 1741, 1794971} and 1031 + 1741 = 2772 = 1301 + 1471. - Marius A. Burtea, Nov 20 2019

#21 by Marius A. Burtea at Wed Nov 20 07:37:42 EST 2019

COMMENTS

#20 by Marius A. Burtea at Wed Nov 20 07:15:58 EST 2019

PROG

(MAGMA) f:=func<n|Intseq(n) eq Reverse(Intseq(n))>; g:=func<n|[&+Divisors(n)] eq [&+[Seqint(Reverse(Intseq(d))):d in Divisors(n)]]>; [k:k in [1..80000]| g(k) and not forall{d:d in Divisors(k)|f(d)}]; // Marius A. Burtea, Nov 20 2019

STATUS

proposed

editing