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

1,2

Links

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

Example

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.

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 *)

Crossrefs

Cf. A000203, A069192, A069942.

Sequence in context: A161383 A062179 A122875 * A166461 A275772 A071242

Adjacent sequences: A080713 A080714 A080715 * A080717 A080718 A080719

Keyword

base,nonn

Author

Joseph L. Pe, Mar 05 2003

Status

approved