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A342021
Numbers k such that
A003415
(sigma(k)) = k, where
A003415
is the arithmetic derivative, and sigma is the sum of divisors of n.
2
5, 8, 41, 47057
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OFFSET
1,1
COMMENTS
a(5) > 2^33, if it exists.
LINKS
Table of n, a(n) for n=1..4.
CROSSREFS
Cf.
A000203
,
A003415
.
Fixed points of
A342925
, Positions of 0's in
A342926
.
Subsequence of
A343217
.
Cf. also
A347889
.
Sequence in context:
A258786
A192272
A073930
*
A130223
A126750
A256401
Adjacent sequences:
A342018
A342019
A342020
*
A342022
A342023
A342024
KEYWORD
nonn
,
more
,
hard
AUTHOR
Antti Karttunen
, Apr 08 2021
STATUS
approved
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Last modified May 9 23:14 EDT 2024. Contains 372354 sequences. (Running on oeis4.)