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.

A211012 Total area of all squares and rectangles after 2^n stages in the toothpick structure of A139250, assuming the toothpicks have length 2.

Original entry on oeis.org

0, 0, 8, 48, 224, 960, 3968, 16128, 65024, 261120, 1046528, 4190208, 16769024, 67092480, 268402688, 1073676288, 4294836224, 17179607040, 68718952448, 274876858368, 1099509530624, 4398042316800, 17592177655808, 70368727400448, 281474943156224
Offset: 0

Views

Author

Omar E. Pol, Sep 21 2012

Keywords

Comments

All internal regions in the toothpick structure are squares and rectangles. The area of every internal region is a power of 2.
Similar to A271061. - Robert Price, Mar 30 2016
For n=3,5,..., also the number of minimum vertex colorings in the n-sunlet graph. - Eric W. Weisstein, Mar 03 2024

Examples

			For n = 3 the area of all squares and rectangles in the toothpick structure after 2^3 stages equals the area of a rectangle of size 8X6, so a(3) = 8*6 = 48.
		

Crossrefs

Row sums of triangle A211017, n>=1.

Programs

  • PARI
    concat(vector(2), Vec(8*x^2/((1-2*x)*(1-4*x)) + O(x^50))) \\ Colin Barker, Mar 30 2016

Formula

a(n) = 2^n * (2^n-2) = A000079(n)*(A000079(n) - 2) = A159786(2^n) = 8*A006516(n-1), n>=1.
From Colin Barker, Mar 30 2016: (Start)
G.f.: 8*x^2 / ((1-2*x)*(1-4*x)).
a(n) = 6*a(n-1)-8*a(n-2) for n>2. (End)
E.g.f.: (1 - exp(2*x))^2. - Stefano Spezia, Mar 12 2025

A211016 Triangle read by rows: T(n,k) = number of squares and rectangles of area 2^(k-1) after 2^n stages in the toothpick structure of A139250, n>=1, k>=1, assuming the toothpicks have length 2.

Original entry on oeis.org

0, 0, 4, 8, 12, 4, 40, 52, 12, 4, 168, 212, 52, 12, 4, 680, 852, 212, 52, 12, 4, 2728, 3412, 852, 212, 52, 12, 4, 10920, 13652, 3412, 852, 212, 52, 12, 4, 43688, 54612, 13652, 3412, 852, 212, 52, 12, 4, 174760, 218452, 54612, 13652, 3412, 852, 212, 52, 12, 4
Offset: 1

Views

Author

Omar E. Pol, Sep 18 2012

Keywords

Comments

All internal regions in the toothpick structure are squares and rectangles.

Examples

			For n = 5 in the toothpick structure after 2^5 stages we have that:
T(5,1) = 168 is the number of squares of size 1 X 1.
T(5,2) = 212 is the number of rectangles of size 1 X 2.
T(5,3) = 52 is the total number of squares of size 2 X 2 and of rectangles of size 1 X 4.
T(5,4) = 12 is the number of rectangles of size 2 X 4.
T(5,5) = 4 is the number of rectangles of size 2 X 8.
Triangle begins:
       0;
       0,      4;
       8,     12,     4;
      40,     52,    12,     4;
     168,    212,    52,    12,    4;
     680,    852,   212,    52,   12,   4;
    2728,   3412,   852,   212,   52,  12,   4;
   10920,  13652,  3412,   852,  212,  52,  12,  4;
   43688,  54612, 13652,  3412,  852, 212,  52, 12,  4;
  174760, 218452, 54612, 13652, 3412, 852, 212, 52, 12, 4;
		

Crossrefs

Row sums give 0 together with A145655.

Formula

T(n,k) = A211008(2^n,k) = 4*A211019(n,k).
T(n,1) = 4*A020988(n-2), n>=2.

A211017 T(n,k) = total area of all squares and rectangles of area 2^(k-1) after 2^n stages in the toothpick structure of A139250, n>=1, k>=1, assuming the toothpicks have length 2. Triangle read by rows.

Original entry on oeis.org

0, 0, 8, 8, 24, 16, 40, 104, 48, 32, 168, 424, 208, 96, 64, 680, 1704, 848, 416, 192, 128, 2728, 6824, 3408, 1696, 832, 384, 256, 10920, 27304, 13648, 6816, 3392, 1664, 768, 512, 43688, 109924, 54608, 27296, 13632, 6784, 3328, 1536, 1024
Offset: 1

Views

Author

Omar E. Pol, Sep 21 2012

Keywords

Comments

All internal regions in the toothpick structure are squares and rectangles. The area of every internal region is a power of 2.

Examples

			For n = 5 in the toothpick structure after 2^5 stages we have that:
T(5,1) = 168 is the total area of all squares of size 1 X 1.
T(5,2) = 424 is the total area of all rectangles of size 1 X 2.
T(5,3) = 208 is the total area of all squares of size 2 X 2 and of all rectangles of size 1 X 4.
T(5,4) = 96 is the total area of all rectangles of size 2 X 4.
T(5,5) = 64 is the total area of all rectangles of size 2 X 8.
Triangle begins:
      0;
      0,     8;
      8,    24,    16;
     40,   104,    48,   32;
    168,   424,   208,   96,   64;
    680,  1704,   848,  416,  192,  128;
   2728,  6824,  3408, 1696,  832,  384, 256;
  10920, 27304, 13648, 6816, 3392, 1664, 768, 512;
		

Crossrefs

Formula

T(n,k) = A211016(n,k)*2^(k-1).
T(n,1) = 4*A020988(n-2), n>=2.

A211019 Triangle read by rows: T(n,k) = number of squares and rectangles of area 2^(k-1) after 2^n stages in the toothpick structure of A139250, divided by 4, n>=1, k>=1, assuming the toothpicks have length 2.

Original entry on oeis.org

0, 0, 1, 2, 3, 1, 10, 13, 3, 1, 42, 53, 13, 3, 1, 170, 213, 53, 13, 3, 1, 682, 853, 213, 53, 13, 3, 1, 2730, 3413, 853, 213, 53, 13, 3, 1, 10922, 13653, 3413, 853, 213, 53, 13, 3, 1, 43690, 54613, 13653, 3413, 853, 213, 53, 13, 3, 1, 174762, 218453
Offset: 1

Views

Author

Omar E. Pol, Sep 24 2012

Keywords

Comments

All internal regions in the toothpick structure are squares and rectangles.

Examples

			Triangle begins:
0;
0,         1;
2,         3,     1;
10,       13,     3,    1;
42,       53,    13,    3,   1;
170,     213,    53,   13,   3,   1;
682,     853,   213,   53,  13,   3,  1;
2730,   3413,   853,  213,  53,  13,  3,  1;
10922, 13653,  3413,  853, 213,  53, 13,  3, 1;
43690, 54613, 13653, 3413, 853, 213, 53, 13, 3, 1;
		

Crossrefs

Row sums give 0 together with A014825.

Formula

T(n,k) = A211016(n,k)/4.
T(n,1) = A020988(n-2), n>=2.
Showing 1-4 of 4 results.