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.

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A000433 n written in base where place values are positive cubes.

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 15, 16, 17, 20, 21, 22, 23, 24, 25, 26, 27, 30, 31, 32, 100, 101, 102, 103, 104, 105, 106, 107, 110, 111, 112, 113, 114, 115, 116, 117, 120, 121, 122, 123, 124, 125, 126, 127, 130, 131, 132, 200, 201, 202, 203
Offset: 0

Views

Author

R. Muller

Keywords

Comments

Let [d1, d2, d3, ...] be the decimal expansion of the n-th term, then dk is the number of times that the greedy algorithm subtracts the cube k^3 with input n. - Joerg Arndt, Nov 21 2014
For n > 1: A048766(n) = number of digits of a(n); A190311(n) = number of nonzero digits of a(n); A055401(n) = sum of digits of a(n). - Reinhard Zumkeller, May 08 2011
First differs from numbers written in base 8 (A007094) at a(27) = 100, whereas A007094(27) = 33. - Alonso del Arte, Nov 27 2014
The rightmost (least significant) digit never exceeds 7, the second digit from the right never exceeds 3, the third digit never exceeds 2, and the rest are just 0's and 1's. - Ivan Neretin, Sep 03 2015

Examples

			a(26) = 32 because 26 = 3 * 2^3 + 2 * 1^3.
a(27) = 100 because 27 = 3^3 + 0 * 2^3 + 0 * 1^3.
a(28) = 101 because 28 = 3^3 + 0 * 2^3 + 1 * 1^3.
		

References

  • Florentin Smarandache, "Properties of the Numbers", University of Craiova Archives, 1975; Arizona State University Special Collections, Tempe, AZ.

Crossrefs

Programs

  • Haskell
    import Data.Char (intToDigit)
    a000433 0 = 0
    a000433 n = read $ map intToDigit $
      t n $ reverse $ takeWhile (<= n) $ tail a000578_list where
          t _ []          = []
          t m (x:xs)
              | x > m     = 0 : t m xs
              | otherwise = (fromInteger m') : t r xs where (m',r) = divMod m x
    -- Reinhard Zumkeller, May 08 2011

A129011 a(n) = floor(n^(4/3)).

Original entry on oeis.org

0, 1, 2, 4, 6, 8, 10, 13, 16, 18, 21, 24, 27, 30, 33, 36, 40, 43, 47, 50, 54, 57, 61, 65, 69, 73, 77, 81, 85, 89, 93, 97, 101, 105, 110, 114, 118, 123, 127, 132, 136, 141, 145, 150, 155, 160, 164, 169, 174, 179, 184, 189, 194, 199, 204, 209, 214, 219, 224, 229, 234
Offset: 0

Views

Author

Jonathan Vos Post, May 01 2007

Keywords

Comments

Churchhouse (1971), as an early example of the use of computers in number theory, conjectured that every positive integer N is the sum of two elements of this sequence and verified the conjecture up to N = 10,000 using the Atlas 1 computer of the Atlas Computer Laboratory at Chilton, U.K. He was able to prove that every sufficiently large integer, N, can be expressed in the form N = floor(n^s) + floor(m^s), n and m being positive integers and s being any number in the interval (1, 4/3). - Peter Bala, Jan 13 2013

References

  • J. Spencer, E. Szemeredi and W. T. Trotter, Unit distances in the Euclidean plane, Graph Theory and Combinatorics, B. Bollabas editor, London: Academic Press, 1984, pp. 293-308.

Crossrefs

Programs

Formula

a(n) = floor(n^(4/3)) = A048766(A000583(n)).

Extensions

More terms from Robert G. Wilson v, May 02 2007

A214081 a(n) = floor( n^(1/3) )!.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24
Offset: 0

Views

Author

Mohammad K. Azarian, Dec 22 2012

Keywords

Crossrefs

Programs

  • Derive
    PROG(y := [], n := 70, LOOP(IF(n = -1, RETURN y), y := ADJOIN(FLOOR(n^(1/3))!, y), n := n - 1))
    
  • Magma
    [Factorial(Floor(n^(1/3))): n in [0..80]]; // Vincenzo Librandi, Feb 13 2013
    
  • Mathematica
    Table[Floor[n^(1/3)]!, {n, 0, 100}] (* T. D. Noe, Dec 23 2012 *)
    Floor[CubeRoot[Range[0,90]]]! (* Harvey P. Dale, Jan 15 2024 *)
  • PARI
    a(n) = floor(n^(1/3))!; \\ Altug Alkan, Jan 11 2016

Formula

Sum_{n>=0} 1/a(n) = 10*e. - Amiram Eldar, Aug 15 2022
a(n) = A000142(A048766(n)). - Michel Marcus, Aug 15 2022

A283760 Expansion of (Sum_{i>=1} x^prime(i))*(Sum_{j>=1} x^(j^3)).

Original entry on oeis.org

0, 0, 1, 1, 0, 1, 0, 1, 0, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 0, 0, 1, 1, 0, 1, 0, 1, 2, 1, 2, 0, 1, 0, 0, 1, 2, 1, 1, 0, 1, 0, 2, 1, 1, 0, 1, 1, 1, 1, 0, 0, 1, 1, 1, 0, 1, 0, 1, 1, 1, 0, 1, 0, 1, 2, 2, 2, 1, 1, 1, 0, 2, 2, 0, 1, 0, 1, 2, 2, 0, 1, 1, 0, 1, 2, 1, 0, 1, 1, 0, 1, 1, 1, 0, 1, 2, 0, 1, 1, 1, 0, 1, 2, 1, 1, 1, 1, 2, 2
Offset: 1

Views

Author

Ilya Gutkovskiy, Mar 16 2017

Keywords

Comments

Number of representations of n as the sum of a prime number and a positive cube.

Examples

			a(32) = 2 because 32 = 31 + 1^3 = 5 + 3^3.
		

Crossrefs

Programs

  • Mathematica
    nmax = 120; Rest[CoefficientList[Series[Sum[x^Prime[i], {i, 1, nmax}] Sum[x^j^3, {j, 1, nmax}], {x, 0, nmax}], x]]
  • PARI
    concat([0,0], Vec((sum(i=1, 120, x^prime(i)) * sum(j=1, 120, x^(j^3))) + O(x^121))) \\ Indranil Ghosh, Mar 16 2017
    
  • Scheme
    (define (A283760 n) (cond ((< n 2) 0) (else (let loop ((k (A048766 n)) (s 0)) (if (< k 1) s (loop (- k 1) (+ s (A010051 (- n (expt k 3)))))))))) ;; Antti Karttunen, Aug 18 2017

Formula

G.f.: (Sum_{i>=1} x^prime(i))*(Sum_{j>=1} x^(j^3)).

A381042 Alternating sum of floor(n^(1/k)), with k >= 2.

Original entry on oeis.org

0, 0, 0, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 3, 3, 3, 3, 3, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 7, 7, 7, 7, 7
Offset: 0

Views

Author

Friedjof Tellkamp, Apr 14 2025

Keywords

Examples

			n:       0, 1, 2, 3, 4, 5, 6, 7, 8, 9, ...
k=2 (+): 0, 1, 1, 1, 2, 2, 2, 2, 2, 3, ... (A000196)
k=3 (-): 0, 1, 1, 1, 1, 1, 1, 1, 2, 2, ... (A048766)
...
Sum:     0, 0, 0, 0, 1, 1, 1, 1, 0, 1 ... (= this sequence).
		

Crossrefs

Cf. A000196 (k=2), A048766 (k=3), A255270 (k=4), A178487 (k=5), A178489 (k=6).
Cf. A089361 (nonalternating), A382691, A382692.

Programs

  • Mathematica
    z = 100; Table[Sum[(-1)^k Floor[n^(1/k)], {k, 2, 2 Floor@Log[2, z/2] - 1}], {n, 0, z}]

Formula

a(n) = A000196(n) - A048766(n) + A255270(n) - A178487(n) + ... .
a(n) = Sum_{k>=2} (-1)^k * floor(n^(1/k)) = Sum_{k>=1} (floor(n^(1/(2*k))) - floor(n^(1/(2*k+1)))).
a(n) = Sum_{i=1..n} A382691(i).
a(n) ~ A382692(n).
G.f.: Sum_{j>=1, k>=2} (-1)^k * x^(j^k)/(1-x).

A064524 Number of noncubes <= n.

Original entry on oeis.org

0, 0, 1, 2, 3, 4, 5, 6, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 60, 61, 62, 63, 64, 65, 66, 67, 68
Offset: 0

Views

Author

Reinhard Zumkeller, Oct 07 2001

Keywords

Crossrefs

Programs

  • PARI
    a(n) = n - sqrtnint(n, 3); \\ Michel Marcus, Jun 18 2024
    
  • Python
    from sympy import integer_nthroot
    def A064524(n): return n-integer_nthroot(n,3)[0] # Chai Wah Wu, Jun 18 2024

Formula

a(n) = n - floor(CubicRoot(n)) = n-A048766(n).
G.f.: x/(1 - x)^2 - (1/(1 - x))*Sum_{k>=1} x^(k^3). - Ilya Gutkovskiy, Feb 16 2017

A095396 Modified juggler map: for even numbers: a(n) = floor(n^(2/3)) and for odd n: a(n) = floor(n^(3/2)) = floor(sqrt(n^3)).

Original entry on oeis.org

1, 1, 5, 2, 11, 3, 18, 4, 27, 4, 36, 5, 46, 5, 58, 6, 70, 6, 82, 7, 96, 7, 110, 8, 125, 8, 140, 9, 156, 9, 172, 10, 189, 10, 207, 10, 225, 11, 243, 11, 262, 12, 281, 12, 301, 12, 322, 13, 343, 13, 364, 13, 385, 14, 407, 14, 430, 14, 453, 15, 476, 15, 500, 16, 524, 16, 548, 16
Offset: 1

Views

Author

Labos Elemer, Jun 18 2004

Keywords

Comments

Parallel to A094683: values for odd arguments are same, for even not necessarily so.

Crossrefs

Programs

  • Mathematica
    d[x_]:=d[x]=(1-Mod[x, 2])*Floor[N[x^(2/3), 50]] +Mod[x, 2]*Floor[N[x^(3/2), 50]];d[1]=1; Table[d[w], {w, 1, 150}]
    Table[If[EvenQ[n],Floor[n^(2/3)],Floor[n^(3/2)]],{n,70}] (* Harvey P. Dale, Dec 28 2018 *)
  • Scheme
    (define (A095396 n) (if (even? n) (A048766 (* n n)) (A000196 (* n n n)))) ;; Antti Karttunen, May 28 2017

Formula

For even n: a(n) = A048766(n^2), for odd n: a(n) = A000196(n^3). - Antti Karttunen, May 28 2017

Extensions

Name simplified by Antti Karttunen, May 28 2017

A134917 a(n) = ceiling(n^(4/3)).

Original entry on oeis.org

1, 3, 5, 7, 9, 11, 14, 16, 19, 22, 25, 28, 31, 34, 37, 41, 44, 48, 51, 55, 58, 62, 66, 70, 74, 78, 81, 86, 90, 94, 98, 102, 106, 111, 115, 119, 124, 128, 133, 137, 142, 146, 151, 156, 161, 165, 170, 175, 180, 185, 190, 195, 200
Offset: 1

Views

Author

Mohammad K. Azarian, Nov 17 2007

Keywords

Crossrefs

Programs

A190311 Number of nonzero digits when writing n in base where place values are positive cubes, cf. A000433.

Original entry on oeis.org

0, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 2, 3, 3, 3, 3, 3, 3, 3, 2, 3, 3, 1, 2, 2, 2, 2, 2, 2, 2, 2, 3, 1, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 2, 3, 3, 3, 3, 3
Offset: 0

Views

Author

Reinhard Zumkeller, May 08 2011

Keywords

Comments

For n > 0: a(A000578(n)) = 1; for n > 1: a(A001093(n)) = 2;
a(n) <= A048766(n).

Crossrefs

Programs

  • Haskell
    a190311 n = g n $ reverse $ takeWhile (<= n) $ tail a000578_list where
      g _ []                 = 0
      g m (x:xs) | x > m     = g m xs
                 | otherwise = signum m' + g r xs where (m',r) = divMod m x

A276614 The infinite trunk of greedy cubes beanstalk with reversed subsections.

Original entry on oeis.org

0, 7, 26, 21, 14, 63, 59, 52, 47, 40, 33, 124, 115, 110, 103, 96, 89, 84, 77, 70, 215, 208, 201, 194, 187, 183, 176, 171, 164, 157, 150, 145, 138, 131, 342, 339, 330, 318, 311, 304, 299, 292, 285, 278, 274, 267, 262, 255, 248, 241, 236, 229, 222, 511, 506, 499, 492, 487, 480, 473, 466, 457, 445, 438, 431, 426, 419, 412, 405, 401
Offset: 0

Views

Author

Antti Karttunen, Sep 07 2016 and Sep 09 2016

Keywords

Crossrefs

Programs

  • Scheme
    (definec (A276614 n) (cond ((zero? n) n) ((= n 1) 7) (else (let ((maybe_next (A261225 (A276614 (- n 1))))) (if (zero? (A010057 (+ 1 maybe_next))) maybe_next (+ -1 (A000578 (+ 2 (A048766 (+ 1 maybe_next))))))))))

Formula

a(0) = 0; a(1) = 7; for n > 1, if A261225(a(n-1))+1 is not a cube, then a(n) = A261225(a(n-1)), otherwise a(n) = A000578(2+A048766(A261225(a(n-1)))) - 1.
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