Search: id:A030285
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%I A030285
%S A030285 0,1,2,3,4,5,6,7,8,9,11,22,33,44,55,66,77,88,99,101,222,303,414,505,616,
%T A030285 707,818,909,1111,2002,3113,4004,5115,6006,7117,8008,9119,20002,31113,
%U A030285 40004,51115,60006,71117,80008,91119,200002,311113,400004
%N A030285 Palindromes whose digits do not appear in previous term.
%C A030285 Although the sequence is infinite, in a sense it cycles. The outside 
               of the next palindrome beginning with 20 continues 31, 40, 51, 60, 
               71, 80, 91 and back to 20. The inside oscillates between increasing 
               number of zeros and ones.
%t A030285 NextPalindrome[n_] := Block[{l = Floor[Log[10, n] + 1], idn = IntegerDigits[n]}, 
               If[ Union[idn] == {9}, Return[n + 2], If[l < 2, Return[n + 1], If[ 
               FromDigits[ Reverse[ Take[idn, Ceiling[l/2]]]] FromDigits[ Take[idn, 
               -Ceiling[l/2]]], FromDigits[ Join[ Take[idn, Ceiling[l/2]], Reverse[ 
               Take[idn, Floor[l/2]]]]], idfhn = FromDigits[ Take[idn, Ceiling[l/
               2]]] + 1; idp = FromDigits[ Join[ IntegerDigits[idfhn], Drop[ Reverse[ 
               IntegerDigits[idfhn]], Mod[l, 2]]]]]]]]; a[0] = 0; a[n_] := a[n] 
               = Block[{k = a[n - 1], d = IntegerDigits[a[n - 1]]}, While[ Intersection[d, 
               IntegerDigits[k]] != {}, k = NextPalindrome[k]]; k]; Table[ a[n], 
               {n, 0, 50}]
%Y A030285 Sequence in context: A062687 A109882 A109872 this_sequence A048321 A071267 
               A110784
%Y A030285 Adjacent sequences: A030282 A030283 A030284 this_sequence A030286 A030287 
               A030288
%K A030285 nonn,base
%O A030285 1,3
%A A030285 Patrick De Geest (pdg(AT)worldofnumbers.com)
%E A030285 Edited by Robert G. Wilson v (rgwv(AT)rgwv.com), Jun 27 2003

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