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.

A249073 Ordered union of the sets {h^6, h >=1} and {2*k^6, k >=1}.

Original entry on oeis.org

1, 2, 64, 128, 729, 1458, 4096, 8192, 15625, 31250, 46656, 93312, 117649, 235298, 262144, 524288, 531441, 1000000, 1062882, 1771561, 2000000, 2985984, 3543122, 4826809, 5971968, 7529536, 9653618, 11390625, 15059072, 16777216, 22781250, 24137569, 33554432
Offset: 1

Views

Author

Clark Kimberling, Oct 21 2014

Keywords

Comments

Let S = {h^6, h >=1} and T = {2*k^6, k >=1}. Then S and T are disjoint. The position of n^6 in the ordered union of S and T is A249123(n), and the position of 2*n^6 is A249124(n).

Examples

			{h^6, h >=1} = {1, 64, 729, 4096, 15625, 46656, 117649, ...};
{2*k^6, k >=1} = {2, 128, 1458, 8192, 31250, 93312, ...};
so the union is {1, 2, 64, 128, 729, 1458, 4096, 8192, 15625, ...}.
		

Crossrefs

Programs

  • Mathematica
    z = 120; s = Table[h^6, {h, 1, z}]; t = Table[2 k^6, {k, 1, z}]; v = Union[s, t]
    Flatten[Table[{n^6,2n^6},{n,20}]]//Union (* Harvey P. Dale, Dec 19 2015 *)

A184808 n + floor(r*n), where r = sqrt(2/3); complement of A184809.

Original entry on oeis.org

1, 3, 5, 7, 9, 10, 12, 14, 16, 18, 19, 21, 23, 25, 27, 29, 30, 32, 34, 36, 38, 39, 41, 43, 45, 47, 49, 50, 52, 54, 56, 58, 59, 61, 63, 65, 67, 69, 70, 72, 74, 76, 78, 79, 81, 83, 85, 87, 89, 90, 92, 94, 96, 98, 99, 101, 103, 105, 107, 108, 110, 112, 114, 116
Offset: 1

Views

Author

Clark Kimberling, Jan 22 2011

Keywords

Comments

This is the Beatty sequence for 1 + sqrt(2/3).
Also, a(n) is the position of 2*n^2 in the sequence obtained by arranging all the numbers in the sets {2*h^2, h >= 1} and {3*k^2, k >= 1} in increasing order. - Clark Kimberling, Oct 20 2014
Also, numbers n such that floor((n+1)*sqrt(6)) - floor(n*sqrt(6)) = 2. - Clark Kimberling, Jul 15 2015

Crossrefs

Cf. A184809, A182760 (comment about joint ranking),

Programs

  • Magma
    [n+Floor(n*Sqrt(2/3)): n in [1..70]]; // Vincenzo Librandi, Oct 23 2014
    
  • Mathematica
    r=(2/3)^(1/2); s=(3/2)^(1/2);
    a[n_]:=n+Floor [n*r];
    b[n_]:=n+Floor [n*s];
    Table[a[n],{n,1,120}]  (* A184808 *)
    Table[b[n],{n,1,120}]  (* A184809 *)
  • PARI
    main(size)={return(vector(size, n, n+floor(sqrt(2/3)*n)))} /* Anders Hellström, Jul 15 2015 */

Formula

a(n) = n + floor(r*n), where r = sqrt(2/3).

A249367 Numbers of the form 2n^2 or 3n^2.

Original entry on oeis.org

0, 2, 3, 8, 12, 18, 27, 32, 48, 50, 72, 75, 98, 108, 128, 147, 162, 192, 200, 242, 243, 288, 300, 338, 363, 392, 432, 450, 507, 512, 578, 588, 648, 675, 722, 768, 800, 867, 882, 968, 972, 1058, 1083, 1152, 1200, 1250, 1323, 1352, 1452, 1458, 1568, 1587, 1682
Offset: 1

Views

Author

M. F. Hasler, Oct 26 2014

Keywords

Comments

Union of 2*A000290 = A001105 and 3*A000290 = A033428.
Essentially a duplicate of A249096.

Crossrefs

A249096 is essentially the same sequence.

Programs

  • Maple
    N:= 10000: # to get all terms <= N
    {seq(2*i^2,i=0..floor(sqrt(N/2)))} union {seq(3*i^2,i=0..floor(sqrt(N/3)))};
    # if using Maple 11 or earlier, uncomment the following line:
    # sort(convert(%,list));
    # Robert Israel, Oct 27 2014
  • PARI
    for(n=0,5000,if(issquare(n/3)||issquare(n/2),print1(n,", "))) \\ Derek Orr, Oct 26 2014

Formula

{2, 3} * A000290 = A001105 U A033428.
Showing 1-3 of 3 results.