OFFSET
1,1
COMMENTS
Without the non-palindromic condition, the first 62 terms would be identical to the list of palindromes A002113. - M. F. Hasler, May 13 2025
LINKS
Donovan Johnson, Table of n, a(n) for n = 1..1000
EXAMPLE
sigma(528) = sigma(825) = 1488.
MATHEMATICA
nd[x_, y_] := 10*x+y tn[x_] := Fold[nd, 0, x] red[x_] := Reverse[IntegerDigits[x]] Do[s=DivisorSigma[1, n]; s1=DivisorSigma[1, tn[red[n]]]; If[Equal[s, s1]&&!Equal[n, tn[red[n]]], Print[{n, s}]], {n, 1, 1000000}]
srnQ[n_]:=Module[{idn=IntegerDigits[n], ridn}, ridn=Reverse[idn]; idn!=ridn && DivisorSigma[1, n]==DivisorSigma[1, FromDigits[ridn]]]; Select[Range[ 100000], srnQ] (* Harvey P. Dale, Oct 25 2011 *)
Select[Range[90000], !PalindromeQ[#]&&DivisorSigma[1, #]==DivisorSigma[1, IntegerReverse[#]]&] (* Harvey P. Dale, Sep 09 2025 *)
PROG
(PARI) select( {is_A085329(n, r=A004086(n))=sigma(n)==sigma(r)&&n!=r}, [1..50000]) \\ M. F. Hasler, May 13 2025
(Python)
from sympy import divisor_sigma as sigma
def is_A085329(n): return sigma(n)==sigma(r:=int(str(n)[::-1])) and n!=r # M. F. Hasler, May 13 2025
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Labos Elemer, Jul 04 2003
STATUS
approved