cp's OEIS Frontend

A240265 Numbers that divide the concatenation of their aliquot divisors, in ascending order.

%I A240265 #17 Feb 18 2021 00:46:21
%S A240265 1,4,15,16,255,375,495,795,1469,3825,9375,28125,66375,67875,234375,
%T A240265 249487,286875,309375,337185,450615,590625,628125,1369125,2390625,
%U A240265 2773125,2781387,3069375,3706785,4965309,5859375,12890625,13539375,26803125,39607575,62578125
%N A240265 Numbers that divide the concatenation of their aliquot divisors, in ascending order.
%C A240265 The sequence is infinite, because it contains all the numbers of the form 3*5^(2k+1). - _Giovanni Resta_, Apr 03 2014
%e A240265 Aliquot divisors of 1469 are 1, 13, 113. Their concatenation in ascending order is 113113 and 113113/1469 = 77.
%p A240265 with(numtheory);
%p A240265 T:=proc(t) local x,y; x:=t; y:=0; while x>0 do x:=trunc(x/10); y:=y+1; od; end:
%p A240265 P:=proc(q) local a,b,c,d,i,k,n;
%p A240265 for n from 2 to q do a:=sort([op(divisors(n))]); b:=a[nops(a)-1];
%p A240265 for i from nops(a)-2 by -1 to 1 do b:=b+a[i]*10^T(b); od;
%p A240265 if type(b/n,integer) then print(n); fi;
%p A240265 od; end: P(10^6);
%t A240265 Select[Range[6258*10^4],Divisible[FromDigits[Flatten[IntegerDigits/@ Most[ Divisors[ #]]]],#]&] (* _Harvey P. Dale_, Aug 21 2019 *)
%Y A240265 Cf. A069872, A224930.
%K A240265 nonn,base
%O A240265 1,2
%A A240265 _Paolo P. Lava_, Apr 03 2014
%E A240265 a(14)-a(34) from _Giovanni Resta_, Apr 03 2014
%E A240265 First term (a(1) = 1) prepended by _Harvey P. Dale_, Aug 21 2019