A251810 Numbers n such that if m = reverse(sigma(n)-n) then n = reverse(sigma(m)-m).

6, 741, 973, 4056, 4296, 41642, 49222, 425822, 457042, 498906, 831805, 998462, 20671542, 41673714, 73687923, 4158499614, 54809993252, 67820167555

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

Table of n, a(n) for n=1..18.

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

Adjacent sequences: A251807 A251808 A251809 * A251811 A251812 A251813

Keyword

nonn,base,more

Author

Paolo P. Lava, Dec 09 2014

Extensions

a(13)-a(18) from Hiroaki Yamanouchi, Sep 11 2015

Status

approved