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A281555 Consider any concatenation of the type n = concat(a,b). Sequence lists numbers whose reverses are the sum of the products of some of such couples a and b.

%I A281555 #9 Jan 25 2017 08:40:40
%S A281555 351,621,886,1641,1901,2401,4122,4322,5101,6568,23913,30591,46649,
%T A281555 60291,90877,199001,216322,223471,237391,297498,394391,405278,420552,
%U A281555 425322,430762,456478,470149,546649,861226,910001,920781,1740821,2008541,2329876,2348812,2414722
%N A281555 Consider any concatenation of the type n = concat(a,b). Sequence lists numbers whose reverses are the sum of the products of some of such couples a and b.
%e A281555 3*51 = 153;
%e A281555 6*21 = 126;
%e A281555 8*86 = 688;
%e A281555 1*641 + 16*41 + 164*1 = 1461;
%e A281555 1*901 + 190*1 = 1091.
%p A281555 with(combinat): with(numtheory): T:=proc(w) local x, y, z; x:=w; y:=0;
%p A281555 for z from 1 to ilog10(x)+1 do y:=10*y+(x mod 10); x:=trunc(x/10); od; y; end:
%p A281555 P:=proc(q) local a, j, k,n; for n from 1 to q do a:={};
%p A281555 for k from 1 to ilog10(n) do a:=a union {(n mod 10^k)*trunc(n/10^k)}; od; a:=choose(a);
%p A281555 for k from 2 to nops(a) do if T(n)=add(a[k][j], j=1..nops(a[k])) then print(n); break; fi; od;
%p A281555 od; end: P(10^9);
%t A281555 Select[Range[10^5], Function[w, MemberQ[Total /@ Rest@ Subsets@ Map[Times @@ Map[FromDigits@ # &, TakeDrop[w, #]] &, Range[Length@ w - 1]], FromDigits@ Reverse@ w]]@ IntegerDigits@ # &] (* _Michael De Vlieger_, Jan 24 2017, Version 10.3 *)
%Y A281555 Cf. A265737, A267939.
%K A281555 nonn,base
%O A281555 1,1
%A A281555 _Paolo P. Lava_, Jan 24 2017