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A258786 Numbers n whose sum of anti-divisors is a permutation of their digits. 1
5, 8, 41, 56, 64, 358, 614, 946, 1092, 1382, 1683, 2430, 2683, 2734, 2834, 2945, 3045, 3067, 3602, 4056, 4286, 5186, 5784, 6874, 7251, 8104, 8546, 9264, 12881, 14028, 14384, 15258, 17386, 21103, 22044, 23331, 24434, 24603, 25346, 26420, 26822, 26845, 27024, 27232 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

A073930 is a subset of this sequence.

LINKS

Paolo P. Lava, Table of n, a(n) for n = 1..200

EXAMPLE

Anti-divisors of 5 are 2, 3 whose sum is 5.

Anti-divisors of 41 are 2, 3, 9, 27 whose sum is 41.

Anti-divisors of 64 are 3, 43 whose sum is 46 that is a permutation of the digit of 64.

MAPLE

with(numtheory):P:=proc(q) local a, b, j, k, ok, n, p;

for n from 1 to q do k:=0; j:=n;

while j mod 2 <> 1 do k:=k+1; j:=j/2; od;

a:=sigma(2*n+1)+sigma(2*n-1)+sigma(n/2^k)*2^(k+1)-6*n-2;

if ilog10(n)=ilog10(a) then j:=sort(convert(n, base, 10)); a:=sort(convert(a, base, 10)); ok:=1;

for k from 1 to nops(a) do if j[k]<>a[k] then ok:=0; break;

fi; od; if ok=1 then print(n); fi; fi; od; end: P(10^9);

MATHEMATICA

ad[n_] := Cases[Range[2, n - 1], _?(Abs[Mod[n, #] - #/2] < 1 &)]; Select[Range@ 5000, SameQ[DigitCount@ #, DigitCount[Total[ad@ #]]] &] (* Michael De Vlieger, Jun 10 2015 *)

PROG

(Python)

from sympy.ntheory.factor_ import antidivisors

A258786_list = [n for n in range(1, 10**5) if sorted(str(n)) == sorted(str(sum(antidivisors(n))))] # Chai Wah Wu, Jun 11 2015

CROSSREFS

Cf. A066417, A073930, A114065, A115920, A115921, A175795, A225902.

Sequence in context: A280965 A151349 A298935 * A192272 A073930 A130223

Adjacent sequences:  A258783 A258784 A258785 * A258787 A258788 A258789

KEYWORD

nonn,base

AUTHOR

Paolo P. Lava, Jun 10 2015

STATUS

approved

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Last modified March 29 03:09 EDT 2020. Contains 333104 sequences. (Running on oeis4.)