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%I A300796 #10 Sep 24 2021 18:56:42
%S A300796 3762,4125,4865,5135,5875,6238,37620,41250,42825,44571,48650,48839,
%T A300796 49496,50504,51161,51350,55429,57175,58750,62380,376200,389232,397584,
%U A300796 399441,412500,417864,428250,434355,436185,445710,446369,472535,481325,483662,483792,486500
%N A300796 Numbers x whose 10's complements y have the same sum of divisors of x, with x <> y.
%C A300796 Many patterns can be found, e.g. 3762*10^j, 4125*10^j, 4865*10^j, 5135*10^j, 5875*10^j, 6238*10^j, etc.
%e A300796 3762 is in the sequence because sigma(3762) = sigma(10^4-3762) = 9360.
%e A300796 5875 is in the sequence because sigma(5875) = sigma(10^4-5875) = 7488.
%p A300796 with(numtheory): P:=proc(q) local a,n;
%p A300796 for n from 1 to q do a:=10^(ilog10(n)+1)-n;
%p A300796 if n<>a and sigma(n)=sigma(a) then print(n); fi; od; end: P(10^6);
%t A300796 c10Q[n_]:=Module[{c=10^IntegerLength[n]-n},c!=n&&DivisorSigma[1,n] == DivisorSigma[1,c]]; Select[Range[500000],c10Q] (* _Harvey P. Dale_, Sep 24 2021 *)
%Y A300796 Cf. A000203, A055120, A300447.
%K A300796 nonn,base,easy
%O A300796 1,1
%A A300796 _Paolo P. Lava_, Mar 13 2018

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