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 1-7 of 7 results.

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 *)

A240510 Numbers whose "reverse and add" process becomes palindromic at 8813200023188.

Original entry on oeis.org

89, 98, 187, 286, 385, 583, 682, 781, 869, 880, 968, 1297, 1387, 1477, 1567, 1657, 1747, 1837, 1927, 2296, 2386, 2476, 2566, 2656, 2746, 2836, 2926, 3295, 3385, 3475, 3565, 3655, 3745, 3835, 3925, 4294, 4384, 4474, 4564, 4654, 4744, 4834, 4924, 5293, 5383
Offset: 1

Views

Author

J. Lowell, Apr 06 2014

Keywords

Comments

The "reverse and add" sequence for 178 includes 8813200023188, but it becomes palindromic at 15851, so 178 is not in this sequence.
See interesting patterns of the first differences in A328492. - Robert Price, Oct 16 2019

References

  • David Wells, The Penguin Dictionary of Curious and Interesting Numbers. Penguin Books, NY, 1986, Revised edition 1987. See p. 143.

Crossrefs

Programs

  • Mathematica
    limit = 10^3; (* Assumes that there is no palindrome if none is found before "limit" iterations *)
    Select[Range[0, 50000], (np = #; i = 0;
       While[ ! PalindromeQ[np] && i < limit,
        np = np + IntegerReverse[np]; i++];
    np == 8813200023188) &] (* Robert Price, Oct 16 2019 *)
  • PARI
    is(n)=my(k=8813200023188); while(n<=k && (d=digits(n))!=(r=Vecrev(d)), n+=fromdigits(r)); n==k; \\ Charles R Greathouse IV, Apr 09 2020

Extensions

More terms from Jon E. Schoenfield, Apr 12 2014

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 *)

A328492 First differences of A240510 (Numbers whose "reverse and add" process becomes palindromic at 8813200023188).

Original entry on oeis.org

9, 89, 99, 99, 198, 99, 99, 88, 11, 88, 329, 90, 90, 90, 90, 90, 90, 90, 369, 90, 90, 90, 90, 90, 90, 90, 369, 90, 90, 90, 90, 90, 90, 90, 369, 90, 90, 90, 90, 90, 90, 90, 369, 90, 90, 90, 90, 90, 90, 90, 369, 90, 90, 90, 90, 90, 90, 90, 369, 90, 90, 90, 90
Offset: 1

Views

Author

Robert Price, Oct 16 2019

Keywords

Comments

Additional patterns can be seen in the bfile.

Crossrefs

Programs

  • Mathematica
    limit = 10^3; (* Assumes that there is no palindrome if none is found before "limit" iterations *)
    Differences@Select[Range[0, 50000], (np = #; i = 0;
        While[ ! PalindromeQ[np] && i < limit,
         np = np + IntegerReverse[np]; i++];
    np == 8813200023188) &] (* Robert Price, Oct 16 2019 *)
Showing 1-7 of 7 results.