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.

Previous Showing 21-24 of 24 results.

A135678 Floor(n^(4/3)+n).

Original entry on oeis.org

2, 4, 7, 10, 13, 16, 20, 24, 27, 31, 35, 39, 43, 47, 51, 56, 60, 65, 69, 74, 78, 83, 88, 93, 98, 103, 108, 113, 118, 123, 128, 133, 138, 144, 149, 154, 160, 165, 171, 176, 182, 187, 193, 199, 205, 210, 216, 222, 228, 234, 240
Offset: 1

Views

Author

Mohammad K. Azarian, Dec 01 2007

Keywords

Crossrefs

Programs

A139179 Number of non-fourth-powers <= n.

Original entry on oeis.org

0, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 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, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70
Offset: 0

Views

Author

Jonathan Vos Post, Jun 06 2008

Keywords

Crossrefs

Programs

  • Mathematica
    a[n_] := n - Floor[n^(1/4)]; a /@ Range[0, 72] (* Giovanni Resta, Jun 21 2016 *)
  • Python
    from sympy import integer_nthroot
    def A139179(n): return n-integer_nthroot(n,4)[0] # Chai Wah Wu, Jun 18 2024

Formula

a(n) = n - floor(n^(1/4)).

Extensions

Offset corrected by Giovanni Resta, Jun 21 2016

A317369 a(0) = 0, a(1) = 1; for n >= 2, a(n) = freq(a(n-s(n)),n) where s = A000196 and freq(i, j) is the number of times i appears in the terms a(0) .. a(j-1).

Original entry on oeis.org

0, 1, 1, 2, 2, 2, 3, 3, 2, 2, 2, 6, 6, 6, 3, 3, 3, 3, 6, 6, 6, 6, 7, 7, 7, 7, 7, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 13, 13, 13, 13, 13, 13, 6, 6, 6, 6, 6, 6, 6, 20, 20, 20, 20, 20, 20, 20, 7, 7, 7, 7, 7, 7, 7, 7, 13, 13, 13, 13, 13, 13, 13, 13, 14, 14, 14, 14, 14, 14, 14, 14, 14, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9
Offset: 0

Views

Author

Altug Alkan, Jul 26 2018

Keywords

Crossrefs

Programs

  • Mathematica
    Nest[Append[#1, Count[#1, #1[[-Floor@ Sqrt@ #2]] ]] & @@ {#, Length@ #} &, {0, 1}, 92] (* Michael De Vlieger, Jul 27 2018 *)

A338621 Triangle read by rows: A(n, k) is the number of partitions of n with "aft" value k (see comments).

Original entry on oeis.org

1, 1, 2, 2, 1, 2, 2, 1, 2, 2, 3, 2, 2, 4, 3, 2, 2, 4, 5, 2, 2, 2, 4, 6, 7, 1, 2, 2, 4, 6, 9, 6, 1, 2, 2, 4, 6, 10, 11, 7, 2, 2, 4, 6, 10, 13, 14, 5, 2, 2, 4, 6, 10, 14, 19, 15, 5, 2, 2, 4, 6, 10, 14, 21, 22, 17, 3, 2, 2, 4, 6, 10, 14, 22, 27, 29, 17, 2, 2, 2, 4, 6, 10, 14, 22, 29, 36, 33, 17
Offset: 0

Views

Author

Joshua Swanson, Nov 04 2020

Keywords

Comments

The "aft" of an integer partition is the number of cells minus the larger of the number of parts or the largest part. For example, aft(4, 2, 2) = 8-4 = 4 = aft(3, 3, 1, 1).
Columns stabilize to twice the partition numbers: A(n, k) = 2p(n) = A139582(n) if n > 2k.
Row sums are partition numbers A000041.
Maximum value of k in row n is n - ceiling(sqrt(n)) = (n-1) - floor(sqrt(n-1)) = A028391(n-1).

Examples

			A(6, 2) = 4 since there are four partitions with 6 cells and aft 2, namely (4, 2), (2, 2, 1, 1), (4, 1, 1), (3, 1, 1, 1).
Triangle starts:
  1;
  1;
  2;
  2, 1;
  2, 2, 1;
  2, 2, 3;
  2, 2, 4, 3;
  2, 2, 4, 5,  2;
  2, 2, 4, 6,  7,  1;
  2, 2, 4, 6,  9,  6,  1;
  2, 2, 4, 6, 10, 11,  7;
  2, 2, 4, 6, 10, 13, 14,  5;
  2, 2, 4, 6, 10, 14, 19, 15,  5;
  2, 2, 4, 6, 10, 14, 21, 22, 17,  3;
  2, 2, 4, 6, 10, 14, 22, 27, 29, 17,  2;
  2, 2, 4, 6, 10, 14, 22, 29, 36, 33, 17,  1;
  2, 2, 4, 6, 10, 14, 22, 30, 41, 45, 39, 15,  1;
  2, 2, 4, 6, 10, 14, 22, 30, 43, 52, 57, 41, 14;
  2, 2, 4, 6, 10, 14, 22, 30, 44, 57, 69, 67, 47, 11;
  2, 2, 4, 6, 10, 14, 22, 30, 44, 59, 76, 85, 81, 46, 9; ...
		

References

  • S. C. Billey, M. Konvalinka, and J. P. Swanson, Asymptotic normality of the major index on standard tableaux, Adv. in Appl. Math. 113 (2020).

Crossrefs

Programs

  • Mathematica
    CoefficientList[
    SeriesCoefficient[
      1 + Sum[If[r == 0, 1, 2] q^(r + 1) Sum[
          q^(2 s) t^s QBinomial[2 s + r, s, q t], {s, 0, 30}], {r, 0,
         30}], {q, 0, 20}], t]
  • PARI
    Row(n)={if(n==0, [1], my(v=vector(n)); forpart(p=n, v[1+n-max(#p, p[#p])]++); Vecrev(Polrev(v)))}
    { for(n=1, 15, print(Row(n))) } \\ Andrew Howroyd, Nov 04 2020

Formula

G.f.: Sum_{lambda} t^aft(lambda) * q^|lambda| = 1 + Sum_{r >= 0} c_r * q^(r+1) * Sum_{s >= 0} q^(2*s) * t^s * [2*s + r, s]_(q*t) where c_0 = 1, c_r = 2 for r >= 1, and [a, b]_q is a Gaussian binomial coefficient (see A022166).
Previous Showing 21-24 of 24 results.