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 1-10 of 10 results.

A145734 Indices of palindromes in A033648.

Original entry on oeis.org

1, 2, 4, 5, 7, 10, 23, 32
Offset: 1

Views

Author

Dmitry Kamenetsky, Oct 17 2008

Keywords

Comments

The next term (if it exists) is greater than 10000.
These are actually indices into A033648 right-shifted; A033648 has offset 0, but this sequence treats it as having offset 1.

Crossrefs

A001127 Trajectory of 1 under map x->x + (x-with-digits-reversed).

Original entry on oeis.org

1, 2, 4, 8, 16, 77, 154, 605, 1111, 2222, 4444, 8888, 17776, 85547, 160105, 661166, 1322332, 3654563, 7309126, 13528163, 49710694, 99312488, 187733887, 976071668, 1842242347, 9274664828, 17559329557, 93151725128, 175304440267, 937348843838, 1775697687577
Offset: 0

Views

Author

N. J. A. Sloane, Jun 05 2002

Keywords

Comments

Normally one stops as soon as a palindrome is reached.
A Reverse and Add! sequence.
Trajectories of 25, 34, 43, 52, 59, 61, 68, 70, 86, 95, ..., merge into this sequence. - Robert G. Wilson v, Dec 16 2005

Crossrefs

Programs

  • Haskell
    a001127 n = a001127_list !! n
    a001127_list = iterate a056964 1 -- Reinhard Zumkeller, Sep 22 2011
  • Maple
    a:= proc(n) option remember; `if`(n=0, 1, (h-> h+ (s->
          parse(cat(s[-i]$i=1..length(s))))(""||h))(a(n-1)))
        end:
    seq(a(n), n=0..40);  # Alois P. Heinz, Jun 18 2014
  • Mathematica
    NestList[ # + FromDigits@Reverse@IntegerDigits@# &, 1, 30] (* Robert G. Wilson v, Dec 16 2005 *)
    NestList[#+IntegerReverse[#]&,1,30] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Nov 19 2019 *)

A243238 Table T(n,r) of terms in the reverse and add sequences of positive integers n read by antidiagonals.

Original entry on oeis.org

1, 2, 2, 4, 4, 3, 8, 8, 6, 4, 16, 16, 12, 8, 5, 77, 77, 33, 16, 10, 6, 154, 154, 66, 77, 11, 12, 7, 605, 605, 132, 154, 22, 33, 14, 8, 1111, 1111, 363, 605, 44, 66, 55, 16, 9, 2222, 2222, 726, 1111, 88, 132, 110, 77, 18, 10, 4444, 4444, 1353, 2222, 176, 363, 121, 154, 99, 11, 11
Offset: 1

Views

Author

Felix Fröhlich, Jun 12 2014

Keywords

Examples

			T(5,6) = 88, since 88 is the 6th term in the reverse and add sequence of 5.
Table starts with:
  1 2 4 8 16 77 154 605 1111 2222
  2 4 8 16 77 154 605 1111 2222 4444
  3 6 12 33 66 132 363 726 1353 4884
  4 8 16 77 154 605 1111 2222 4444 8888
  5 10 11 22 44 88 176 847 1595 7546
  6 12 33 66 132 363 726 1353 4884 9768
  7 14 55 110 121 242 484 968 1837 9218
  8 16 77 154 605 1111 2222 4444 8888 17776
  9 18 99 198 1089 10890 20691 40293 79497 158994
  10 11 22 44 88 176 847 1595 7546 14003
		

Crossrefs

Rows n=1, 3, 5, 7, 9 give: A001127, A033648, A033649, A033650, A033651.
Main diagonal gives A244058.

Programs

  • Maple
    T:= proc(n, r) option remember; `if`(r=1, n, (h-> h +(s->
          parse(cat(s[-i]$i=1..length(s))))(""||h))(T(n, r-1)))
        end:
    seq(seq(T(n, 1+d-n), n=1..d), d=1..12);  # Alois P. Heinz, Jun 18 2014
  • Mathematica
    rad[n_] := n + FromDigits[Reverse[IntegerDigits[n]]];
    T[n_, 1] := n; T[n_, k_] := T[n, k] = rad[T[n, k-1]];
    Table[T[n-k+1, k], {n, 1, 12}, {k, n, 1, -1}] // Flatten (* Jean-François Alcover, Apr 08 2016 *)

A033650 Trajectory of 7 under map x --> x + (x-with-digits-reversed).

Original entry on oeis.org

7, 14, 55, 110, 121, 242, 484, 968, 1837, 9218, 17347, 91718, 173437, 907808, 1716517, 8872688, 17735476, 85189247, 159487405, 664272356, 1317544822, 3602001953, 7193004016, 13297007933, 47267087164, 93445163438, 176881317877, 955594506548, 1801200002107
Offset: 0

Views

Author

Keywords

Comments

A Reverse and Add! sequence.
Trajectories of 19, 23, 28, 29, 32, 37, 38, 41, 46, 47, 49, 50, ..., merge into this sequence. - Robert G. Wilson v, Dec 16 2005
A Reverse and Add! sequence.

Crossrefs

Programs

  • Haskell
    a033650 n = a033650_list !! n
    a033650_list = iterate a056964 7 -- Reinhard Zumkeller, Sep 22 2011
  • Maple
    a:= proc(n) option remember; `if`(n=0, 7, (h-> h+ (s->
          parse(cat(s[-i]$i=1..length(s))))(""||h))(a(n-1)))
        end:
    seq(a(n), n=0..40);  # Alois P. Heinz, Jun 18 2014
  • Mathematica
    NestList[ # + FromDigits@Reverse@IntegerDigits@# &, 7, 26] (* Robert G. Wilson v *)

A033651 Trajectory of 9 under map x->x + (x-with-digits-reversed).

Original entry on oeis.org

9, 18, 99, 198, 1089, 10890, 20691, 40293, 79497, 158994, 658845, 1207701, 2284722, 4559544, 9019098, 17928207, 88211178, 175322466, 839546037, 1570191975, 7362102726, 13634115363, 49985258994, 99970517988, 188942025987, 978462275868, 1847034540747, 9317488848228
Offset: 0

Views

Author

Keywords

Comments

Trajectories of 27, 36, 45, 54, 63, 72, 81, 90, ..., merge into this sequence. - Robert G. Wilson v, Dec 16 2005.

Crossrefs

Row n=9 of A243238.
Partial sums of A112296.

Programs

  • Haskell
    a063051 n = a063051_list !! n
    a063051_list = iterate a056964 879 -- Reinhard Zumkeller, Sep 22 2011
  • Maple
    a:= proc(n) option remember; `if`(n=0, 9, (h-> h+ (s->
          parse(cat(s[-i]$i=1..length(s))))(""||h))(a(n-1)))
        end:
    seq(a(n), n=0..40);  # Alois P. Heinz, Jun 18 2014
  • Mathematica
    NestList[ # + FromDigits@Reverse@IntegerDigits@# &, 9, 26] (* Robert G. Wilson v *)

A033649 Trajectory of 5 under map x->x + (x-with-digits-reversed).

Original entry on oeis.org

5, 10, 11, 22, 44, 88, 176, 847, 1595, 7546, 14003, 44044, 88088, 176176, 847847, 1596595, 7553546, 14007103, 44177144, 88354288, 176599676, 853595347, 1597190705, 6668108656, 13236127322, 35608290553
Offset: 0

Views

Author

Keywords

Comments

Trajectories of 15, 21, 24, 30, 39, 42, 48, 51, 57, 60, 69, 75, 78, 84, 87, 93, 96, ..., merge into this sequence. - Robert G. Wilson v, Dec 16 2005
A Reverse and Add! sequence.
Trajectories of 13, 17, 20, 26, 31, 35, 40, 53, 62, 71, 79, 80, 97, ..., merge into this sequence. - Robert G. Wilson v, Dec 16 2005

Crossrefs

Programs

  • Haskell
    a033649 n = a033649_list !! n
    a033649_list = iterate a056964 5 -- Reinhard Zumkeller, Sep 22 2011
  • Maple
    a:= proc(n) option remember; `if`(n=0, 5, (h-> h+ (s->
          parse(cat(s[-i]$i=1..length(s))))(""||h))(a(n-1)))
        end:
    seq(a(n), n=0..40);  # Alois P. Heinz, Jun 18 2014
  • Mathematica
    NestList[ # + FromDigits@Reverse@IntegerDigits@# &, 5, 29] (* Robert G. Wilson v, Dec 16 2005 *)

A244567 Triangle T(n,k) in which the n-th row lists in increasing order all values s such that n is in the trajectory of the 'Reverse and Add!' sequence starting with s; triangle T(n,k), n>=0, 1<=k<=A244569(n), read by rows.

Original entry on oeis.org

0, 1, 1, 2, 3, 1, 2, 4, 5, 3, 6, 7, 1, 2, 4, 8, 9, 5, 10, 5, 10, 11, 3, 6, 12, 13, 7, 14, 15, 1, 2, 4, 8, 16, 17, 9, 18, 19, 20, 21, 5, 10, 11, 20, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 3, 6, 12, 21, 30, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43
Offset: 0

Views

Author

Alois P. Heinz, Jun 30 2014

Keywords

Examples

			Triangle T(n,k) begins:
   0;
   1;
   1,  2;
   3;
   1,  2,  4;
   5;
   3,  6;
   7;
   1,  2,  4,  8;
   9;
   5, 10;
   5, 10, 11;
   3,  6, 12;
  13;
   7, 14;
  15;
   1,  2,  4,  8,  16;
  17;
		

Crossrefs

Column k=0 gives A244568.
Last elements of rows give A001477.

A244568 Smallest value s such that n is in the trajectory of the 'Reverse and Add!' sequence starting with s.

Original entry on oeis.org

0, 1, 1, 3, 1, 5, 3, 7, 1, 9, 5, 5, 3, 13, 7, 15, 1, 17, 9, 19, 20, 21, 5, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 3, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 5, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 7, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 3, 67, 68, 69
Offset: 0

Views

Author

Alois P. Heinz, Jun 30 2014

Keywords

Crossrefs

A244569 Number of values s such that n is in the trajectory of the 'Reverse and Add!' sequence starting with s.

Original entry on oeis.org

1, 1, 2, 1, 3, 1, 2, 1, 4, 1, 2, 3, 3, 1, 2, 1, 5, 1, 2, 1, 1, 1, 5, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 6, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 9, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 7, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 12, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 12, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 17
Offset: 0

Views

Author

Alois P. Heinz, Jun 30 2014

Keywords

Crossrefs

A244058 n-th term of the 'Reverse and Add!' sequence starting with n.

Original entry on oeis.org

1, 4, 12, 77, 44, 363, 484, 4444, 79497, 14003, 88088, 175857, 1596595, 1716517, 17794887, 13528163, 176599676, 839546037, 1317544822, 853595347, 8836886388, 13236127322, 13297007933, 668823329856, 175304440267, 909153350908, 9317488848228, 8813200023188
Offset: 1

Views

Author

Alois P. Heinz, Jun 18 2014

Keywords

Comments

a(n) is a palindrome for n in {1, 2, 4, 5, 6, 7, 8, 9, 11, 21, 28, 30}.

Crossrefs

Main diagonal of A243238.

Programs

  • Maple
    b:= proc(n, j) option remember; `if`(j=1, n, (h-> h+ (s->
          parse(cat(s[-i]$i=1..length(s))))(""||h))(b(n, j-1)))
        end:
    a:= n-> b(n$2):
    seq(a(n), n=1..40);
  • Mathematica
    Table[Nest[#+IntegerReverse[#]&,n,n-1],{n,30}] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jun 07 2021 *)
Showing 1-10 of 10 results.