A118561 Lucky numbers for which the reversal is also a lucky number.
1, 3, 7, 9, 13, 15, 31, 33, 37, 51, 73, 99, 111, 115, 133, 141, 151, 163, 169, 171, 189, 193, 195, 303, 327, 331, 339, 361, 385, 391, 393, 399, 511, 529, 535, 537, 579, 583, 591, 717, 723, 727, 729, 735, 739, 777, 787, 925, 927, 933, 937, 961, 975, 979, 981, 993
Offset: 1
Examples
133 is in the sequence because (1) it is a lucky number and (2) the reversal 331 is also a lucky number.
Links
- Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..9014 from T. D. Noe)
- W. Schneider, The First 1,000 Lucky Number.
Programs
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Mathematica
nn = 10^3; t = Range[1, nn, 2]; sieve[n_] := Module[{k = t[[n]]}, t = Delete[t, Table[{i}, {i, k, Length[t], k}]]]; n = 1; While[t[[n]] < Length[t], n++; sieve[n]]; tr = Table[FromDigits[Reverse[IntegerDigits[i]]], {i, t}]; Intersection[t, tr] (* T. D. Noe, Mar 16 2013 *)
Extensions
Corrected and extended by Adam Panagos (adam.panagos(AT)gmail.com), May 10 2006
957 removed by T. D. Noe, Mar 16 2013
Comments