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A357678
Numbers k equal to the integer log of the sum of k and its digit reversal.
0
8, 17, 107
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OFFSET
1,1
COMMENTS
10^n + 7 is a term if 10^n + 1 is prime, however that is conjectured to occur only for n = 0, 1 and 2.
No further terms < 2*10^8.
LINKS
Table of n, a(n) for n=1..3.
EXAMPLE
a(3) = 107 is a term because the integer log of (107 + 701 = 808 = 2^3*101) is 3*2 + 101 = 107.
MAPLE
rev:= proc(n) local L, i; L:= convert(n, base, 10): add(L[-i]*10^(i-1), i=1..nops(L)) end proc:
filter:= proc(n) local s, t;
s:= n + rev(n);
n = add(t[1]*t[2], t=ifactors(s)[2])
end proc:
select(filter, [$1..10^6]);
CROSSREFS
Cf.
A001414
,
A004086
,
A056964
.
Sequence in context:
A350683
A177129
A177178
*
A097405
A192282
A088588
Adjacent sequences:
A357675
A357676
A357677
*
A357679
A357680
A357681
KEYWORD
nonn
,
base
,
bref
,
more
AUTHOR
J. M. Bergot
and
Robert Israel
, Oct 08 2022
STATUS
approved
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Last modified July 20 03:14 EDT 2024. Contains 374441 sequences. (Running on oeis4.)