OFFSET
1,2
LINKS
Michael De Vlieger, Table of n, a(n) for n = 1..5000
EXAMPLE
sigma(1055) + phi(1055) = 1272 + 840 = 2112.
MATHEMATICA
Select[Range@ 1800, Reverse@ # == # &@ IntegerDigits[DivisorSigma[1, #] + EulerPhi@ #] &] (* Michael De Vlieger, Jul 22 2016 *)
Select[Range[2000], PalindromeQ[DivisorSigma[1, #]+EulerPhi[#]]&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Mar 29 2020 *)
PROG
(PARI) ispal(n)=n=digits(n); Vecrev(n)==n
is(n, f=factor(n))=ispal(sigma(f)+eulerphi(f)) \\ Charles R Greathouse IV, Jul 22 2016
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Giovanni Resta, Feb 06 2006
STATUS
approved