%I
%S 22,187,202,222,242,262,282,302,322,342,362,382,1717,1737,1757,1777,
%T 1797,1817,1837,1857,1877,1897,2002,2871,3982,11211,11411,11611,11811,
%U 12011,12211,12411,12611,12811,17017,18128,18997,19888,20002,20202
%N Numbers n of the form k + reverse(k) for exactly two k.
%C In the cognate sequence A071265 two numbers a and b are counted only once, if n = a + b, a = reverse(b), b = reverse(a). Therefore 187 = 89 + 98 = 98 + 89 does not appear in A071265.
%H <a href="/index/Res#RAA">Index entries for sequences related to Reverse and Add!</a>
%e 22 = 11 + 11 = 20 + 02, 187 = 89 + 98 = 98 + 89, 382 = 191 + 191 = 290 + 092.
%p # Maple program from _N. J. A. Sloane_, Mar 07 2016. Assumes digrev (from the "transforms" file) is available:
%p M:=21000; b := Array(1..M,0);
%p for n from 1 to M do
%p t1:=n+digrev(n);
%p if t1 <= M then b[t1]:=b[t1]+1; fi;
%p od:
%p ans:=[];
%p for n from 1 to M do
%p if b[n]=2 then ans:=[op(ans),n]; fi; od:
%p ans;
%t M = 10^5; digrev[n_] := IntegerDigits[n] // Reverse // FromDigits; Clear[b]; b[_] = 0; For[n = 1, n <= M, n++, t1 = n + digrev[n]; If[t1 <= M, b[t1] = b[t1] + 1]]; A072040 = Reap[For[n = 1, n <= M, n++, If[b[n] == 2, Sow[n]]]][[2, 1]] (* _JeanFrançois Alcover_, Oct 01 2016, after _N. J. A. Sloane_'s Maple code *)
%Y Cf. A067030, A071265, A072041, A096768.
%K base,nonn
%O 1,1
%A _Klaus Brockhaus_, Jun 08 2002
