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.

351, 621, 886, 1641, 1901, 2401, 4122, 4322, 5101, 6568, 23913, 30591, 46649, 60291, 90877, 199001, 216322, 223471, 237391, 297498, 394391, 405278, 420552, 425322, 430762, 456478, 470149, 546649, 861226, 910001, 920781, 1740821, 2008541, 2329876, 2348812, 2414722

Offset: 1

Author

Paolo P. Lava, Jan 24 2017

Keywords

• nonn
• base

Examples

			3*51 = 153;
6*21 = 126;
8*86 = 688;
1*641 + 16*41 + 164*1 = 1461;
1*901 + 190*1 = 1091.
		

Crossrefs

Cf. A265737, A267939.

Programs

Maple

with(combinat): with(numtheory): T:=proc(w) local x, y, z; x:=w; y:=0;
for z from 1 to ilog10(x)+1 do y:=10*y+(x mod 10); x:=trunc(x/10); od; y; end:
P:=proc(q) local a, j, k,n; for n from 1 to q do a:={};
for k from 1 to ilog10(n) do a:=a union {(n mod 10^k)*trunc(n/10^k)}; od; a:=choose(a);
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;
od; end: P(10^9);

Mathematica

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 *)