A066145 In base 2, records for the number of 'Reverse and Add' steps needed to reach a palindrome.

0, 1, 2, 4, 5, 11, 21, 32, 37, 46, 48, 49, 53, 89, 99, 142, 147, 273, 297, 345, 515, 550, 573

Offset

1,3

Comments

The analog of A065199 in base 2. A066144 gives the corresponding starting points.

Terms a(19..22) obtained by assuming that a(n+1) <= a(n) + 300. - A.H.M. Smeets, Apr 30 2022

Links

Table of n, a(n) for n=1..23.

Index entries for sequences related to Reverse and Add!

Example

Starting with 74, 11 'Reverse and Add' steps are needed to reach a palindrome; starting with n < 74, at most 5 steps are needed.

Mathematica

limit = 10^3; (* Assumes that there is no palindrome if none is found before "limit" iterations *)
best = -1; lst = {};
For[n = 0, n <= 10000, n++,
np = n; i = 0;
While[np != IntegerReverse[np, 2] && i < limit,
  np = np + IntegerReverse[np, 2]; i++];
If[i < limit && i > best, best = i; AppendTo[lst, i]]]; lst (* Robert Price, Oct 14 2019 *)

Crossrefs

Record values in base b: A077407 (b=3), A075687 (b=4), A306600 (b=8), A065199 (b=10), A348572 (Zeckendorf).

Cf. A062130, A066057, A066058, A066059, A066144.

Sequence in context: A223220 A113058 A391974 * A095022 A279050 A317828

Adjacent sequences: A066142 A066143 A066144 * A066146 A066147 A066148

Keyword

base,more,nonn

Author

Klaus Brockhaus, Dec 08 2001

Extensions

Offset corrected and a(19)-a(23) by A.H.M. Smeets, Apr 30 2022

Status

approved