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 14 results. Next

A003249 a(n) = A001950(A003234(n)) + 1.

Original entry on oeis.org

8, 21, 29, 42, 50, 55, 63, 76, 84, 97, 110, 118, 131, 139, 144, 152, 165, 173, 186, 194, 199, 207, 220, 228, 241, 254, 262, 275, 283, 288, 296, 309, 317, 330, 338, 343, 351, 364, 372, 377, 385, 398, 406, 419, 427, 432, 440, 453, 461, 474, 487, 495, 508, 516
Offset: 1

Views

Author

Keywords

Comments

This is the function named u' in [Carlitz]. - Eric M. Schmidt, Aug 14 2014

References

  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Cf. A242094 (complement), A001950, A003234.

Programs

Extensions

Corrected and extended by, and a definition from Eric M. Schmidt, Aug 14 2014

A003248 a(n) = A000201(A003234(n)) + n.

Original entry on oeis.org

5, 14, 20, 29, 35, 39, 45, 54, 60, 69, 78, 84, 93, 99, 103, 109, 118, 124, 133, 139, 143, 149, 158, 164, 173, 182, 188, 197, 203, 207, 213, 222, 228, 237, 243, 247, 253, 262, 268, 272, 278, 287, 293, 302, 308, 312, 318, 327, 333, 342, 351, 357, 366, 372, 376
Offset: 1

Views

Author

Keywords

Comments

This is the function named t' in [Carlitz]. - Eric M. Schmidt, Aug 14 2014

References

  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Extensions

More terms and a definition from Eric M. Schmidt, Aug 14 2014

A003254 The number m such that A003233(m) = A005206(A003234(n)).

Original entry on oeis.org

2, 4, 6, 8, 9, 10, 12, 14, 15, 17, 19, 21, 23, 24, 25, 27, 29, 31, 33, 34, 35, 37, 39, 40, 42, 44, 46, 48, 49, 50, 52, 54, 55, 57, 58, 59, 61, 63, 64, 65, 67, 69, 71, 73, 74, 75, 77, 79, 80, 82, 84, 86, 88, 89, 90, 92, 94, 95, 97, 98, 99, 101, 103, 104, 106
Offset: 1

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Author

Keywords

Comments

This is the function named p in [Carlitz]. - Eric M. Schmidt, Aug 14 2014

References

  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Extensions

More terms and a definition from Eric M. Schmidt, Aug 14 2014

A247421 The number m such that A242094(m) = A005206(A003234(n)).

Original entry on oeis.org

2, 5, 7, 9, 11, 12, 14, 17, 19, 21, 24, 26, 28, 30, 31, 33, 36, 38, 40, 42, 43, 45, 47, 49, 51, 54, 56, 58, 60, 61, 63, 66, 68, 70, 72, 73, 75, 77, 79, 80, 82, 85, 87, 89, 91, 92, 94, 97, 99, 101, 104, 106, 108, 110, 111, 113, 116, 118, 120, 122, 123, 125, 127
Offset: 1

Views

Author

Eric M. Schmidt, Sep 16 2014

Keywords

Comments

This is the function named x in [Carlitz].

A003250 The number m such that A001950(m) = A003231(A003234(n)).

Original entry on oeis.org

4, 11, 15, 22, 26, 29, 33, 40, 44, 51, 58, 62, 69, 73, 76, 80, 87, 91, 98, 102, 105, 109, 116, 120, 127, 134, 138, 145, 149, 152, 156, 163, 167, 174, 178, 181, 185, 192, 196, 199, 203, 210, 214, 221, 225, 228, 232, 239, 243, 250, 257, 261, 268, 272, 275, 279
Offset: 1

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Author

Keywords

Comments

This is the function named z in [Carlitz]. - Eric M. Schmidt, Aug 14 2014

References

  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Formula

From Eric M. Schmidt, Aug 14 2014: (Start)
a(n) = ceiling((1/phi^2) * A003231(A003234(n))), where phi is the golden ratio.
a(n) = 5*k - 1 - A003231(k), where k = A003234(n). [Cf. Theorems 4.1(ii) and 5.9(vii) in Carlitz.]
Conjecture: a(n) = floor((3-phi)*A003234(n)).
(End)

Extensions

More terms and a definition from Eric M. Schmidt, Aug 14 2014

A003231 a(n) = floor(n*(sqrt(5)+5)/2).

Original entry on oeis.org

3, 7, 10, 14, 18, 21, 25, 28, 32, 36, 39, 43, 47, 50, 54, 57, 61, 65, 68, 72, 75, 79, 83, 86, 90, 94, 97, 101, 104, 108, 112, 115, 119, 123, 126, 130, 133, 137, 141, 144, 148, 151, 155, 159, 162, 166, 170, 173, 177, 180, 184, 188, 191, 195, 198, 202, 206, 209
Offset: 1

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Author

Keywords

Comments

Let r = (5 - sqrt(5))/2 and s = (5 + sqrt(5))/2. Then 1/r + 1/s = 1, so that A249115 and A003231 are a pair of complementary Beatty sequences. Let tau = (1 + sqrt(5))/2, the golden ratio. Let R = {h*tau, h >= 1} and S = {k*(tau - 1), k >= 1}. Then A003231(n) is the position of n*tau in the ordered union of R and S. The position of n*(tau - 1) is A249115(n). - Clark Kimberling, Oct 21 2014
This is the function named c in the Carlitz-Scoville-Vaughan link. - Eric M. Schmidt, Aug 06 2015
Natural numbers whose representation in base phi differs between the Bergmann representation and the "canonical" representation described by Dekking and van Loon. See proposition 3.3 in Dekking, van Loon (2021). - Hugo Pfoertner, May 26 2023

References

  • Dekking, Michel, and Ad van Loon. "On the representation of the natural numbers by powers of the golden mean." arXiv preprint arXiv:2111.07544 (2021); Fib. Quart. 61:2 (May 2023), 105-118.
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Programs

  • Haskell
    a003231 = floor . (/ 2) . (* (sqrt 5 + 5)) . fromIntegral
    -- Reinhard Zumkeller, Oct 03 2014
    
  • Magma
    [Floor(n*(Sqrt(5)+5)/2): n  in [1..100]]; // Vincenzo Librandi, Oct 23 2014
    
  • Maple
    A003231:=n->floor(n*(sqrt(5)+5)/2): seq(A003231(n), n=1..100); # Wesley Ivan Hurt, Aug 06 2015
  • Mathematica
    With[{c=(Sqrt[5]+5)/2}, Floor[c*Range[60]]] (* Harvey P. Dale, Oct 01 2012 *)
  • PARI
    a(n)=floor(n*(sqrt(5)+5)/2)
    
  • PARI
    a(n)=(5*n+sqrtint(5*n^2))\2; \\ Michel Marcus, Nov 14 2023
    
  • Python
    from math import isqrt
    def A003231(n): return (n+isqrt(5*n**2)>>1)+(n<<1) # Chai Wah Wu, Aug 25 2022

Formula

a(n) = 2*n + A000201(n). - R. J. Mathar, Aug 22 2014

Extensions

Better description and more terms from Michael Somos, Jun 07 2000

A242094 Complement of A003249.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 22, 23, 24, 25, 26, 27, 28, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 43, 44, 45, 46, 47, 48, 49, 51, 52, 53, 54, 56, 57, 58, 59, 60, 61, 62, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74
Offset: 1

Views

Author

Eric M. Schmidt, Aug 14 2014

Keywords

Comments

This is the function named u in [Carlitz].
First differs from A187947 at a(46)=51.

Crossrefs

Cf. A003249.

Programs

A003233 Numbers k such that A003231(A001950(k)) = A001950(A003231(k)).

Original entry on oeis.org

1, 2, 4, 5, 6, 7, 9, 10, 12, 13, 14, 15, 17, 18, 20, 22, 23, 25, 26, 27, 28, 30, 31, 33, 34, 35, 36, 38, 39, 40, 41, 43, 44, 46, 47, 48, 49, 51, 52, 54, 56, 57, 59, 60, 61, 62, 64, 65, 67, 68, 69, 70, 72, 73, 75, 77, 78, 80, 81, 82, 83, 85, 86, 88, 89, 90, 91
Offset: 1

Views

Author

Keywords

Comments

See 3.3 p. 344 in Carlitz link. - Michel Marcus, Feb 02 2014
This is the function named r in [Carlitz]. - Eric M. Schmidt, Aug 14 2014

References

  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Programs

  • Haskell
    a003233 n = a003233_list !! (n-1)
    a003233_list = [x | x <- [1..],
                        a003231 (a001950 x) == a001950 (a003231 x)]
    -- Reinhard Zumkeller, Oct 03 2014
    
  • Mathematica
    a3221[n_] := Floor[n(5 + Sqrt[5])/2];
    a1950[n_] := Floor[n(1 + Sqrt[5])^2/4];
    Select[Range[100], a3221[a1950[#]] == a1950[a3221[#]]&] (* Jean-François Alcover, Aug 04 2018 *)
  • PARI
    A001950(n) = floor(n*(sqrt(5)+3)/2);
    A003231(n) = floor(n*(sqrt(5)+5)/2);
    lista(nn) = { for(n=1, nn, if (A003231(A001950(n)) == A001950(A003231(n)), print1(n, ", ")));} \\ Michel Marcus, Feb 02 2014
    
  • Python
    from math import isqrt
    from itertools import count, islice
    def A003233_gen(startvalue=1): # generator of terms >= startvalue
        return filter(lambda n:((m:=(n+isqrt(5*n**2)>>1)+n)+isqrt(5*m**2)>>1)+(m<<1)==((k:=(n+isqrt(5*n**2)>>1)+(n<<1))+isqrt(5*k**2)>>1)+k,count(max(1,startvalue)))
    A003233_list = list(islice(A003233_gen(),30)) # Chai Wah Wu, Sep 02 2022

Extensions

More terms from Michel Marcus, Feb 02 2014
Definition from Michel Marcus moved from comment to name by Eric M. Schmidt, Aug 17 2014

A003256 a(n) is the number m such that A242094(m) = A001950(n).

Original entry on oeis.org

2, 5, 7, 9, 12, 14, 17, 19, 21, 24, 26, 28, 31, 33, 36, 38, 40, 43, 45, 47, 49, 51, 54, 56, 58, 61, 63, 66, 68, 70, 73, 75, 77, 80, 82, 85, 87, 89, 92, 94, 97, 99, 101, 104, 106, 108, 111, 113, 116, 118, 120, 123, 125, 127, 129, 131, 134, 136, 138, 141, 143
Offset: 1

Views

Author

Keywords

Comments

This is the function named v in [Carlitz]. - Eric M. Schmidt, Aug 14 2014
Ron Reble remarks that Carlitz has a typo on page 339: Carlitz writes "In particular since (b) is a proper subset of (a), there exists a function v such that b = av." It should be "(b) is a proper subset of (u), ... b = uv." - N. J. A. Sloane, Jan 20 2020

References

  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Programs

  • Haskell
    import Data.List (elemIndex); import Data.Maybe (fromJust)
    a003256 = (+ 1) . fromJust . (`elemIndex` a242094_list) . a001950
    -- Reinhard Zumkeller, Oct 03 2014

Formula

a(n) = A001950(n) - j, where j is the largest integer such that A003234(j) < n. [Carlitz, Thm. 7.3]. - Eric M. Schmidt, Sep 16 2014

Extensions

New definition by Eric M. Schmidt, Aug 17 2014

A247423 Complement of A247424.

Original entry on oeis.org

2, 4, 6, 8, 9, 10, 12, 14, 16, 18, 20, 22, 24, 25, 26, 28, 30, 32, 34, 35, 36, 38, 40, 42, 44, 46, 48, 50, 51, 52, 54, 56, 58, 60, 61, 62, 64, 66, 67, 68, 70, 72, 74, 76, 77, 78, 80, 82, 84, 86, 88, 90, 92, 93, 94, 96, 98, 100, 102, 103, 104, 106, 108, 110
Offset: 1

Views

Author

Eric M. Schmidt, Sep 16 2014

Keywords

Comments

This is the function named y in [Carlitz], which defines this sequence by the property A242094(A247419(a(n))) = A005206(A003234(n)).
Showing 1-10 of 14 results. Next