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
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
KEYWORD
nonn,base,more
AUTHOR
Paolo P. Lava, Dec 09 2014
EXTENSIONS
a(13)-a(18) from Hiroaki Yamanouchi, Sep 11 2015
STATUS
approved