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.

A065206 Numbers which need one 'Reverse and Add' step to reach a palindrome.

Original entry on oeis.org

10, 12, 13, 14, 15, 16, 17, 18, 20, 21, 23, 24, 25, 26, 27, 29, 30, 31, 32, 34, 35, 36, 38, 40, 41, 42, 43, 45, 47, 50, 51, 52, 53, 54, 56, 60, 61, 62, 63, 65, 70, 71, 72, 74, 80, 81, 83, 90, 92, 100, 102, 103, 104, 105, 106, 107, 108, 110, 112, 113, 114, 115, 116, 117
Offset: 1

Views

Author

Klaus Brockhaus, Oct 21 2001

Keywords

Comments

The number of steps starts at 0, so palindromes (A002113) are excluded.
Numbers k such that A033665(k) = 1. - Andrew Howroyd, Dec 05 2024

Crossrefs

Programs

  • ARIBAS
    function revadd_steps(k,stop: integer); var c,n,m,steps,rev: integer; begin n := 0; c := 0; while c < stop do m := n; rev := int_reverse(m); steps := 0; while steps < k and m <> rev do m := m + rev; rev := int_reverse(m); inc(steps); end; if steps = k and m = rev then write(n," "); inc(c); end; inc(n); end; end; revadd_steps(1,66).
    
  • Haskell
    a065206 n = a065206_list !! (n-1)
    a065206_list = filter ((== 1) . a136522 . a056964) a029742_list
    -- Reinhard Zumkeller, Oct 14 2011
    
  • Mathematica
    Select[Range[10,120],!PalindromeQ[#]&&PalindromeQ[#+IntegerReverse[#]]&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jun 14 2017 *)
  • PARI
    isok(n,s=1)={for(k=0, s, my(r=fromdigits(Vecrev(digits(n)))); if(r==n, return(k==s)); n += r); 0} \\ Andrew Howroyd, Dec 05 2024

Extensions

Offset corrected by Harry J. Smith, Oct 13 2009

A066133 Numbers that in base 2 need twelve 'Reverse and Add' steps to reach a palindrome.

Original entry on oeis.org

1027, 1139, 1181, 1229, 1433, 1481, 1537, 1649, 1951, 1983, 1999, 2031, 2051, 3073, 3103, 3215, 3351, 3463, 3611, 3639, 3671, 3723, 3751, 3783, 3839, 3859, 3971, 4087, 4103, 4121, 4141, 4187, 4237, 4269, 4327, 4331, 4333, 4361, 4427, 4603, 4625, 4645
Offset: 1

Views

Author

Klaus Brockhaus, Dec 08 2001

Keywords

Comments

The analog of A065217 in base 2. The number of steps starts at 0, so palindromes (cf. A006995) are excluded.
Numbers k such that A066057(k) = 12. - Andrew Howroyd, Dec 05 2024

Crossrefs

Programs

  • PARI
    isok(n,s=12)={for(k=0, s, my(r=fromdigits(Vecrev(binary(n)),2)); if(r==n, return(k==s)); n += r); 0} \\ Andrew Howroyd, Dec 05 2024

Extensions

Offset changed from 0 to 1 by Harry J. Smith, Feb 01 2010

A015993 Twelve iterations of Reverse and Add are needed to reach a palindrome.

Original entry on oeis.org

2069, 2159, 2249, 2339, 2429, 2519, 2609, 2699, 2789, 2879, 2969, 3068, 3158, 3248, 3338, 3428, 3518, 3608, 3698, 3788, 3878, 3968, 4067, 4157, 4247, 4337, 4427, 4517, 4607, 4697, 4787, 4877, 4967, 5066, 5156, 5246, 5336, 5426, 5516
Offset: 1

Views

Author

Keywords

Comments

The number of iterations starts at 1, so palindromes (cf. A002113) are not excluded. This sequence coincides with the corresponding sequence excluding palindromes (A065217) for the entries shown in the database. The first divergence occurs at 10901.

Crossrefs

Showing 1-3 of 3 results.