cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-3 of 3 results.

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

Original entry on oeis.org

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

Views

Author

Klaus Brockhaus, Dec 08 2001

Keywords

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

Examples

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

Links

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.

Programs

  • 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 *)

Extensions

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

A075686 In base 4, n sets a new record for the number of Reverse and Add! steps needed to reach a palindrome starting with n.

Original entry on oeis.org

0, 4, 7, 26, 28, 127, 199, 296, 511, 3119, 16861, 18164, 19453, 20468, 270824
Offset: 0

Views

Author

Klaus Brockhaus, Sep 24 2002

Keywords

Comments

RECORDS transform of A075685. - Base-4 analog of A065198 (base 10) and A066144 (base 2). Integers like 290, for which a palindrome is (presumably) never reached (cf. A075420), are of course disregarded. A075687 gives the corresponding records.

Examples

			Starting with 26, 3 Reverse and Add! steps are needed to reach a palindrome; starting with n < 26, less (at most 2) steps are needed.

Links

Crossrefs

Cf. A065198, A066144, A075420, A075685, A075687.

A077407 In base 3, records for the number of Reverse and Add! steps needed to reach a palindrome.

Original entry on oeis.org

0, 1, 2, 3, 4, 18, 20, 21, 27, 28, 55, 56, 57, 70
Offset: 1

Views

Author

Klaus Brockhaus, Nov 05 2002

Keywords

Comments

RECORDS transform of A077402. Base-3 analog of A066145 (base 2), A075687 (base 4) and A065199 (base 10). A077406 gives the corresponding starting points.
Probable Lychrel numbers are ignored, the first of which is 103. - Sean A. Irvine, Apr 19 2010

Examples

			Starting with 15, 3 Reverse and Add! steps are needed to reach a palindrome; starting with n < 15, less (at most 2) steps are needed.

Links

Crossrefs

Cf. A065199, A066145, A075687, A077402, A077406.

Extensions

a(14) from Sean A. Irvine, Apr 19 2010
Showing 1-3 of 3 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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