A033665 -id:A033665 - cp's OEIS frontend

A222533 Smallest palindrome which requires at least n iterations of Reverse and Add to reach a palindrome.

1, 5, 77, 181, 747, 88, 494, 292, 4664, 9779, 464, 10901, 4884, 1991, 474, 999, 838, 64946, 989, 448844, 48084, 99199, 484, 73137, 48184, 94149, 11911, 390093, 46264, 567765, 26262, 28782, 3541453, 831138, 1447441, 493394, 1309031, 46664, 8817188, 17871

Offset: 1

Arkadiusz Wesolowski, Feb 24 2013

Palindromes themselves are also 'Reverse and Add!'ed!

Arkadiusz Wesolowski, Table of n, a(n) for n = 1..110
Eric Weisstein's World of Mathematics, Reverse-Then-Add Sequence
Index entries for sequences related to palindromes
Index entries for sequences related to Reverse and Add!

Cf. A016016, A033665.

lst = {}; rev[n_] := FromDigits@Reverse@IntegerDigits[n]; testQ[n_] := ! rev[n] == n; Do[n = 1; While[True, If[! testQ[n], p = n + rev[n]; If[Length@TakeWhile[NestList[# + rev[#] &, p, s - 1], testQ] == s - 1, AppendTo[lst, n]; Break[]]]; n++], {s, 40}]; lst

A243824 Two-column array A(n,s) of pairs (n,s) read by row where s is the smallest seed number such that the Reverse and Add! trajectory of s contains n (excluding cases where n=s).

Original entry on oeis.org

2, 1, 4, 1, 6, 3, 8, 1, 10, 5, 11, 5, 12, 3, 14, 7, 16, 1, 18, 9, 22, 5

Offset: 2

Felix Fröhlich, Jun 11 2014

			A(10,1)=16 is in the array because 16 is the 9th number appearing in the Reverse and Add! trajectory of a smaller number.
A(10,2)=1 is in the array because 1 + 1 = 2, 2 + 2 = 4, 4 + 4 = 8, 8 + 8 = 16, so 1 is the smallest seed number whose Reverse and Add! trajectory contains 16.
Array begins:
  2 1
  4 1
  6 3
  8 1
  10 5
  11 5
  12 3
  14 7
  16 1
  18 9
  22 5

Felix Fröhlich, C++ program for this sequence

Cf. A006960, A023109, A033665, A063048, A070788, A077594.

cp's OEIS Frontend

A222533 Smallest palindrome which requires at least n iterations of Reverse and Add to reach a palindrome.

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