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A249300 Composite numbers whose concatenation of their aliquot parts, in ascending order, is a palindrome.

%I A249300 #12 Oct 26 2014 17:32:34
%S A249300 93,121,393,497,755,842,961,993,1042,1255,1293,1642,1681,1893,1897,
%T A249300 3721,3755,3997,4043,4061,4442,5041,5755,6797,8197,8842,9993,11042,
%U A249300 11255,16593,17309,17642,22255,23221,23597,26242,26493,26797,29793,30043,30242,30383
%N A249300 Composite numbers whose concatenation of their aliquot parts, in ascending order, is a palindrome.
%H A249300 Paolo P. Lava, <a href="/A249300/b249300.txt">Table of n, a(n) for n = 1..100</a>
%e A249300 Aliquot parts of 157442 are 1, 2, 78621; their concatenation in ascending order is concat(1,2,78621) = 1278621, which is a palindrome.
%p A249300 with(numtheory): P:=proc(q) local a,b,c,k,n;
%p A249300 for n from 2 to q do if not isprime(n) then a:=sort([op(divisors(n))]); b:=0;
%p A249300 for k from nops(a)-1 by -1 to 1 do b:=b*10^(ilog10(a[k])+1)+a[k]; od; a:=0; c:=b;
%p A249300 for k from 1 to ilog10(b)+1 do a:=10*a+(c mod 10); c:=trunc(c/10); od;
%p A249300 if a=b then print(n); fi; fi; od; end: P(10^9);
%o A249300 (PARI) isok(n) = {d = vecsort(divisors(n)); if (#d > 2, s = ""; for (i=1, #d-1, s = concat(s, Str(d[i]));); d = digits(eval(s)); d == Vecrev(d););} \\ _Michel Marcus_, Oct 25 2014
%Y A249300 Cf. A046449.
%K A249300 nonn,base
%O A249300 1,1
%A A249300 _Paolo P. Lava_, Oct 24 2014