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Numbers n such that sum of the divisors of n equals the sum of the reversals of the divisors of n.
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%I #17 Sep 07 2020 13:25:27

%S 1,2,3,4,5,6,7,8,9,11,22,30,33,42,44,55,66,77,88,99,101,121,131,151,

%T 181,191,202,242,262,303,313,330,353,363,373,383,393,404,462,484,505,

%U 606,626,681,707,727,757,772,787,797,808,824,890,909,919,929,939,989,1111

%N Numbers n such that sum of the divisors of n equals the sum of the reversals of the divisors of n.

%H Amiram Eldar, <a href="/A080716/b080716.txt">Table of n, a(n) for n = 1..8811</a> (terms below 10^10, terms 1..300 from Paolo P. Lava)

%e Sum of divisors of 30: 1+2+3+5+6+10+15+30=72; sum of reversals of divisors of 30: 1+2+3+5+6+1+51+3=72. Therefore 30 belongs to the sequence.

%p isA080716 := proc(n)

%p simplify(A069192(n) = numtheory[sigma](n)) ;

%p end proc:

%p for n from 1 to 1000 do

%p if isA080716(n) then

%p printf("%d,",n) ;

%p end if;

%p end do: # _R. J. Mathar_, Sep 09 2015

%t rev[n_] := FromDigits[Reverse[IntegerDigits[n]]]; Select[Range[10^4], Apply[Plus, Map[rev, Divisors[ # ]]] == DivisorSigma[1, # ] &]

%t Select[Range[1200],Total[IntegerReverse/@Divisors[#]]==DivisorSigma[1,#]&] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Sep 07 2020 *)

%Y Cf. A000203, A069192, A069942.

%K base,nonn

%O 1,2

%A _Joseph L. Pe_, Mar 05 2003