A277258 Numbers such that n+R(n) | n*R(n), where R(n) is the digits reverse of n.
2, 4, 6, 8, 22, 44, 66, 88, 110, 132, 198, 202, 212, 220, 222, 231, 232, 242, 252, 262, 264, 272, 282, 292, 297, 330, 396, 404, 414, 424, 434, 440, 444, 454, 462, 464, 474, 484, 494, 495, 550, 594, 606, 616, 626, 636, 646, 656, 660, 666, 676, 686, 693, 696, 770
Offset: 1
Examples
R(132) = 231, (132 * 231) / (132 + 231) = 30492 / 363 = 84.
Links
- Paolo P. Lava, Table of n, a(n) for n = 1..1000
Programs
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Maple
R:=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 n; for n from 1 to q do if type(n*R(n)/(n+R(n)),integer) then print(n); fi; od; end: P(10^4);
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Mathematica
Select[Range@ 770, Function[r, Mod[# r, # + r] == 0]@ FromDigits@ Reverse@ IntegerDigits@ # &] (* Michael De Vlieger, Oct 14 2016 *)
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PARI
R(n) = eval(concat(Vecrev(Str(n)))); isok(n) = n*R(n) % (n+R(n)) == 0; \\ Michel Marcus, Oct 15 2016
Comments