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.

A271498 Smallest number in the trajectory of n under repeated application of the map k -> A271497(k).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 7, 1, 1, 1, 7, 1, 7, 7, 1, 1, 1, 1, 7, 1, 7, 7, 1, 1, 7, 7, 1, 7, 1, 1, 31, 7, 7, 1, 7, 1, 7, 7, 7, 1, 7, 7, 7, 7, 1, 7, 31, 1, 7, 7, 1, 7, 7, 1, 31, 7, 7, 7, 31, 1, 31, 31, 7, 7, 7, 7, 7, 7, 1, 7, 1, 1, 7, 7, 7, 7, 1, 7, 31, 7, 1, 7, 1, 7, 1, 1, 1, 7, 1, 1, 31, 1, 31, 31, 7, 7, 7, 7
Offset: 1

Views

Author

N. J. A. Sloane, Apr 16 2016

Keywords

Comments

It appears that every number n eventually reaches one of the loops (1,2,3), (7,14,21), (31,62,93), ..., (2^(2*m-1)-1, 2^(2*m)-2, 3*(2^(2*m-1)-1)), ...

Links

Crossrefs

Cf. A271497.

A052008 a(n) = 'n with digits sorted in ascending order' + 'n with digits sorted in descending order'.

Original entry on oeis.org

0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 11, 22, 33, 44, 55, 66, 77, 88, 99, 110, 22, 33, 44, 55, 66, 77, 88, 99, 110, 121, 33, 44, 55, 66, 77, 88, 99, 110, 121, 132, 44, 55, 66, 77, 88, 99, 110, 121, 132, 143, 55, 66, 77, 88, 99, 110, 121, 132, 143, 154, 66, 77, 88, 99, 110, 121
Offset: 0

Views

Author

Patrick De Geest, Nov 15 1999

Keywords

Comments

a(n) = A004185(n) + A004186(n). - Reinhard Zumkeller, Jun 07 2015

Examples

			E.g., n = 19 -> 19 + 91 = 110.

Links

Crossrefs

Cf. A052009; different from A056964.
Cf. A004185, A004186, A271497.

Programs

  • Haskell
    a052008 n = a004185 n + a004186 n  -- Reinhard Zumkeller, Jun 07 2015
  • Mathematica
    f[n_]:=Module[{sidn=Sort[IntegerDigits[n]]},FromDigits[sidn]+ FromDigits[ Reverse[sidn]]]; Array[f,70,0] (* Harvey P. Dale, Nov 13 2011 *)
  • PARI
    for(n=0,100,D=digits(n);R=Vecrev(D);print1(sum(i=1,#D,10^(i-1)*(D[i]+R[i])),", ")) \\ Derek Orr, Feb 26 2017

A271500 Positions of terms greater than 1 in A271498.

Original entry on oeis.org

7, 11, 13, 14, 19, 21, 22, 25, 26, 28, 31, 32, 33, 35, 37, 38, 39, 41, 42, 43, 44, 46, 47, 49, 50, 52, 53, 55, 56, 57, 58, 59, 61, 62, 63, 64, 65, 66, 67, 68, 70, 73, 74, 75, 76, 78, 79, 80, 82, 84, 88, 91, 93, 94, 95, 96, 97, 98, 99, 100, 103, 104, 105, 107, 109, 110, 111, 112, 114, 115, 117, 118, 119
Offset: 1

Views

Author

N. J. A. Sloane, Apr 16 2016

Keywords

Comments

There are several similar sequences in the OEIS, but no exact match. It would be nice to have an independent characterization of these numbers (independent of A271498, that is).

Links

Crossrefs

Cf. A271497, A271498.
Showing 1-3 of 3 results.

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

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