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

69, 78, 87, 96, 174, 175, 181, 183, 191, 192, 195, 273, 274, 280, 282, 290, 291, 294, 372, 373, 381, 390, 393, 471, 472, 480, 492, 539, 570, 571, 579, 591, 599, 629, 638, 649, 670, 678, 679, 690, 698, 699, 728, 729, 737, 748, 749, 769, 777

Offset: 0

Author

Robert G. Wilson v

Keywords

• nonn
• base

Comments

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

Links

• Harvey P. Dale, Table of n, a(n) for n = 0..1000
• Index entries for sequences related to Reverse and Add!

Crossrefs

A002113, A065209.

Programs

Mathematica

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 *)