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

Author

Arkadiusz Wesolowski, Feb 24 2013

Keywords

• base
• nonn

Comments

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

Links

• 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!

Crossrefs

Cf. A016016, A033665.

Programs

Mathematica

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