OFFSET
1,2
LINKS
Robert Israel, Table of n, a(n) for n = 1..2000
EXAMPLE
227+phi(227)+phi(phi(227)) = 565.
MAPLE
filter:= proc(n) local t, x, L;
uses numtheory;
t:= phi(n);
x:= n + t + phi(t);
L:= convert(x, base, 10);
andmap(i -> L[i]=L[-i], [$1..nops(L)/2]);
end proc:
select(filter, [$1..1000]); # Robert Israel, Sep 03 2020
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Giovanni Resta, Feb 13 2006
STATUS
approved