login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A251810 Numbers n such that if m = reverse(sigma(n)-n) then n = reverse(sigma(m)-m). 0
6, 741, 973, 4056, 4296, 41642, 49222, 425822, 457042, 498906, 831805, 998462, 20671542, 41673714, 73687923, 4158499614, 54809993252, 67820167555 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Fixed points of the transform n -> reverse(sigma(reverse(sigma(n)-n))- reverse(sigma(n)-n)).
a(19) > 10^11. - Hiroaki Yamanouchi, Sep 11 2015
LINKS
EXAMPLE
sigma(741)-741 = 379 and reverse(379)=973;
sigma(973)-973 = 147 and reverse(147)=741;
MAPLE
with(numtheory): T:=proc(w) local x, y, z; x:=0; y:=w;
for z from 1 to ilog10(w)+1 do x:=10*x+(y mod 10); y:=trunc(y/10); od; x; end:
P:=proc(q) local a, b, k, n;
for n from 1 to q do if n=T(sigma(T(sigma(n)-n))-T(sigma(n)-n)) then
print(n); fi; od; end: P(10^12);
CROSSREFS
Cf. A000203.
Sequence in context: A354251 A232130 A289365 * A283787 A130688 A214009
KEYWORD
nonn,base,more
AUTHOR
Paolo P. Lava, Dec 09 2014
EXTENSIONS
a(13)-a(18) from Hiroaki Yamanouchi, Sep 11 2015
STATUS
approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 28 14:38 EDT 2024. Contains 371254 sequences. (Running on oeis4.)