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A015980 Four iterations of Reverse and Add are needed to reach a palindrome. 2


%S 69,78,87,96,174,175,181,183,191,192,195,273,274,280,282,290,291,294,

%T 372,373,381,390,393,471,472,480,492,539,570,571,579,591,599,629,638,

%U 649,670,678,679,690,698,699,728,729,737,748,749,769,777

%N Four iterations of Reverse and Add are needed to reach a palindrome.

%C The number of iterations starts at 1, so palindromes (cf. A002113) are not excluded. The corresponding sequence excluding palindromes is A065209.

%H Harvey P. Dale, <a href="/A015980/b015980.txt">Table of n, a(n) for n = 0..1000</a>

%H <a href="/index/Res#RAA">Index entries for sequences related to Reverse and Add!</a>

%t ra4Q[n_]:=With[{c=Rest[NestList[#+IntegerReverse[#]&,n,4]]}, PalindromeQ[ Last[c]] && NoneTrue[Most[c],PalindromeQ]]; Select[Range[800],ra4Q] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, May 28 2018 *)

%Y A002113, A065209.

%K nonn,base

%O 0,1

%A _Robert G. Wilson v_

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Last modified October 20 09:59 EDT 2021. Contains 348100 sequences. (Running on oeis4.)