A080716 Numbers n such that sum of the divisors of n equals the sum of the reversals of the divisors of n.

1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 22, 30, 33, 42, 44, 55, 66, 77, 88, 99, 101, 121, 131, 151, 181, 191, 202, 242, 262, 303, 313, 330, 353, 363, 373, 383, 393, 404, 462, 484, 505, 606, 626, 681, 707, 727, 757, 772, 787, 797, 808, 824, 890, 909, 919, 929, 939, 989, 1111

Offset: 1

Author

Joseph L. Pe, Mar 05 2003

Keywords

• base
• nonn

Examples

			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.
		

Links

• Amiram Eldar, Table of n, a(n) for n = 1..8811 (terms below 10^10, terms 1..300 from Paolo P. Lava)

Crossrefs

Cf. A000203, A069192, A069942.

Programs

Maple

isA080716 := proc(n)
    simplify(A069192(n) = numtheory[sigma](n)) ;
end proc:
for n from 1 to 1000 do
    if isA080716(n) then
        printf("%d,",n) ;
    end if;
end do: # R. J. Mathar, Sep 09 2015

Mathematica

rev[n_] := FromDigits[Reverse[IntegerDigits[n]]]; Select[Range[10^4], Apply[Plus, Map[rev, Divisors[ # ]]] == DivisorSigma[1, # ] &]
Select[Range[1200],Total[IntegerReverse/@Divisors[#]]==DivisorSigma[1,#]&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Sep 07 2020 *)