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 1-4 of 4 results.

A135697 Palindromes formed from the reflected decimal expansion of Pi.

Original entry on oeis.org

3, 33, 313, 3113, 31413, 314413, 3141413, 31411413, 314151413, 3141551413, 31415951413, 314159951413, 3141592951413, 31415922951413, 314159262951413, 3141592662951413, 31415926562951413, 314159265562951413, 3141592653562951413, 31415926533562951413, 314159265353562951413
Offset: 1

Views

Author

Omar E. Pol, Mar 01 2008, Mar 28 2008

Keywords

Comments

Pi = 3.14159265358979323846264338327... (see A000796).
The number of digits of a(n) is equal to n.

Examples

			   n        Digits of a(n)
   1             ( 3 )
   2            ( 3 3 )
   3           ( 3 1 3 )
   4          ( 3 1 1 3 )
   5         ( 3 1 4 1 3 )
   6        ( 3 1 4 4 1 3 )
   7       ( 3 1 4 1 4 1 3 )
   8      ( 3 1 4 1 1 4 1 3 )
   9     ( 3 1 4 1 5 1 4 1 3 )
  10    ( 3 1 4 1 5 5 1 4 1 3 )

Links

Crossrefs

Cf. A000796, A002113, A039954, A138070, A138071.

Programs

  • Mathematica
    Table[FromDigits[Join[#[[;; Floor[n/2]]], #[[Ceiling[n/2] ;; 1 ;; -1]]]], {n, Length[#]}] & [First[RealDigits[Pi, 10, 25]]] (* Paolo Xausa, Dec 09 2024 *)

A138071 Triangle read by rows: row n lists the digits of A135698(n), the palindromic number with odd number of digits formed from the reflected decimal expansion of Pi.

Original entry on oeis.org

3, 3, 1, 3, 3, 1, 4, 1, 3, 3, 1, 4, 1, 4, 1, 3, 3, 1, 4, 1, 5, 1, 4, 1, 3, 3, 1, 4, 1, 5, 9, 5, 1, 4, 1, 3, 3, 1, 4, 1, 5, 9, 2, 9, 5, 1, 4, 1, 3, 3, 1, 4, 1, 5, 9, 2, 6, 2, 9, 5, 1, 4, 1, 3, 3, 1, 4, 1, 5, 9, 2, 6, 5, 6, 2, 9, 5, 1, 4, 1, 3
Offset: 1

Views

Author

Omar E. Pol, Mar 03 2008

Keywords

Comments

Also, successive digits of the numbers A135698(n).

Examples

			Triangle begins:
              3
           3, 1, 3
        3, 1, 4, 1, 3
     3, 1, 4, 1, 4, 1, 3
  3, 1, 4, 1, 5, 1, 4, 1, 3

Links

Crossrefs

Decimal expansion of Pi: A000796. Cf. A119351, A135697, A135698, A138070.

Programs

  • Mathematica
    Table[Join[#[[;; n - 1]], #[[n ;; 1 ;; -1]]], {n, Length[#]}] & [First[RealDigits[Pi, 10, 15]]] (* Paolo Xausa, Dec 08 2024 *)

A139259 Triangle read by rows: row n lists the digits of A139258(n), the palindromic number formed from the reflected decimal expansion of Euler's constant (or Euler-Mascheroni constant) gamma.

Original entry on oeis.org

5, 5, 5, 5, 7, 5, 5, 7, 7, 5, 5, 7, 7, 7, 5, 5, 7, 7, 7, 7, 5, 5, 7, 7, 2, 7, 7, 5, 5, 7, 7, 2, 2, 7, 7, 5, 5, 7, 7, 2, 1, 2, 7, 7, 5, 5, 7, 7, 2, 1, 1, 2, 7, 7, 5, 5, 7, 7, 2, 1, 5, 1, 2, 7, 7, 5, 5, 7, 7, 2, 1, 5, 5, 1, 2, 7, 7, 5
Offset: 1

Views

Author

Omar E. Pol, May 01 2008

Keywords

Comments

Also, successive digits of A139258.

Examples

			Triangle begins:
....... 5
...... 5,5
..... 5,7,5
.... 5,7,7,5
... 5,7,7,7,5

Crossrefs

Decimal expansion of gamma: A001620.
Cf. A138068, A138070, A138072, A139258, A139260, A139261.

Programs

  • Mathematica
    a[n_]:=FromDigits[Join[RealDigits[EulerGamma,10,Ceiling[n/2]][[1]],Reverse[RealDigits[EulerGamma,10,Floor[n/2]][[1]]]]];IntegerDigits/@Array[a,12]//Flatten (* James C. McMahon, Jun 29 2025 *)

A138114 Triangle read by rows: row n lists the first n digits of the decimal expansion of Pi.

Original entry on oeis.org

3, 3, 1, 3, 1, 4, 3, 1, 4, 1, 3, 1, 4, 1, 5, 3, 1, 4, 1, 5, 9, 3, 1, 4, 1, 5, 9, 2, 3, 1, 4, 1, 5, 9, 2, 6, 3, 1, 4, 1, 5, 9, 2, 6, 5, 3, 1, 4, 1, 5, 9, 2, 6, 5, 3, 3, 1, 4, 1, 5, 9, 2, 6, 5, 3, 5, 3, 1, 4, 1, 5, 9, 2, 6, 5, 3, 5, 8
Offset: 1

Views

Author

Omar E. Pol, Mar 14 2008

Keywords

Examples

			Triangle begins:
..... 3
.... 3,1
... 3,1,4
.. 3,1,4,1
. 3,1,4,1,5

Crossrefs

Cf. A000796, A138070, A138071.

Programs

  • Mathematica
    s={};Do[AppendTo[s,RealDigits[Pi,10,n][[1]]],{n,12}];s//Flatten (* James C. McMahon, Jun 05 2025 *)
Showing 1-4 of 4 results.

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