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A116044
n+phi(n)+phi(phi(n)) is a palindrome.
1
1, 2, 3, 4, 5, 6, 14, 23, 28, 45, 51, 55, 56, 63, 75, 79, 85, 95, 136, 138, 146, 161, 168, 169, 186, 189, 195, 201, 227, 231, 241, 247, 272, 274, 275, 276, 292, 297, 306, 322, 323, 336, 389, 398, 418, 423, 430, 444, 473, 504, 514, 543, 552, 555, 567, 574, 582
OFFSET
1,2
LINKS
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
Cf. A115905.
Sequence in context: A249102 A250047 A084830 * A116027 A085157 A065637
KEYWORD
nonn,base
AUTHOR
Giovanni Resta, Feb 13 2006
STATUS
approved