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 1-8 of 8 results.

A173464 When regarded as a triangle, the rows of A162797 converge to this sequence.

Original entry on oeis.org

1, 5, 5, 17, 5, 17, 21, 49, 5, 17, 21, 49, 21, 53, 81, 129, 5, 17, 21, 49, 21, 53, 81, 129, 21, 53, 81, 133, 81, 165, 289, 321
Offset: 1

Views

Author

Omar E. Pol, Feb 22 2010

Keywords

Examples

			From _Omar E. Pol_, Apr 01 2011: (Start)
If written as a triangle begins:
1,
5,
5,17,
5,17,21,49,
5,17,21,49,21,53,81,129,
5,17,21,49,21,53,81,129,21,53,81,133,81,165,289,321,
...
It appears that the final terms of rows give A000337.
It appears that row sums give A010036.
(End)
		

Crossrefs

Extensions

More terms a(20)-a(32) from Omar E. Pol, Apr 01 2011

A162795 Total number of toothpicks in the toothpick structure A139250 that are parallel to the initial toothpick, after n odd rounds.

Original entry on oeis.org

1, 5, 9, 21, 25, 37, 53, 85, 89, 101, 117, 149, 165, 201, 261, 341, 345, 357, 373, 405, 421, 457, 517, 597, 613, 649, 709, 793, 853, 965, 1173, 1365, 1369, 1381, 1397, 1429, 1445, 1481, 1541, 1621, 1637, 1673, 1733, 1817, 1877, 1989, 2197, 2389, 2405, 2441, 2501
Offset: 1

Views

Author

Omar E. Pol, Jul 14 2009

Keywords

Comments

Partial sums of A162793.
Also, total number of ON cells at stage n of the two-dimensional cellular automaton defined as follows: replace every "vertical" toothpick of length 2 with a centered unit square "ON" cell, so we have a cellular automaton which is similar to both A147562 and A169707 (this is the "one-step bishop" version). For the "one-step rook" version we use toothpicks of length sqrt(2), then rotate the structure 45 degrees and then replace every toothpick with a unit square "ON" cell. For the illustration of the sequence as a cellular automaton we now have three versions: the original version with toothpicks, the one-step rook version and one-step bishop version. Note that the last two versions refer to the standard ON cells in the same way as the two versions of A147562 and the two versions of A169707. It appears that the graph of this sequence lies between the graphs of A147562 and A169707. Also, it appears that this sequence shares infinitely many terms with both A147562 and A169707, see Formula section and Example section. - Omar E. Pol, Feb 20 2015
It appears that this is also a bisection (the odd terms) of A255747.

Examples

			From _Omar E. Pol_, Feb 18 2015: (Start)
Written as an irregular triangle T(j,k), k>=1, in which the row lengths are the terms of A011782:
    1;
    5;
    9, 21;
   25, 37, 53, 85;
   89,101,117,149,165,201,261,341;
  345,357,373,405,421,457,517,597,613,649,709,793,853,965,1173,1365;
  ...
The right border gives the positive terms of A002450.
(End)
It appears that T(j,k) = A147562(j,k) = A169707(j,k), if k is a power of 2, for example: it appears that the three mentioned triangles only share the elements of the columns 1, 2, 4, 8, 16, ... - _Omar E. Pol_, Feb 20 2015
		

Crossrefs

Formula

It appears that a(n) = A147562(n) = A169707(n), if n is a term of A048645, otherwise A147562(n) < a(n) < A169707(n). - Omar E. Pol, Feb 20 2015
It appears that a(n) = (A169707(2n) - 1)/4 = A255747(2n-1). - Omar E. Pol, Mar 07 2015
a(n) = 1 + 4*A255737(n-1). - Omar E. Pol, Mar 08 2015

Extensions

More terms from N. J. A. Sloane, Dec 28 2009

A162796 Number of toothpicks in the toothpick structure A139250 that are orthogonal to the initial toothpick after n even rounds.

Original entry on oeis.org

0, 2, 6, 14, 22, 30, 42, 70, 86, 94, 106, 134, 154, 182, 222, 310, 342, 350, 362, 390, 410, 438, 478, 566, 602, 630, 670, 758, 814, 906, 1046, 1302, 1366, 1374, 1386, 1414, 1434, 1462, 1502, 1590, 1626, 1654, 1694, 1782, 1838, 1930, 2070, 2326, 2394, 2422, 2462
Offset: 0

Views

Author

Omar E. Pol, Jul 14 2009

Keywords

Comments

Also, partial sums of A162794.

Crossrefs

Programs

  • Maple
    a139251 := BFILETOLIST("b139251.txt") ; A162794 := proc(n) global a139251; op(2*n,a139251) ; end: A162796 := proc(n) add( A162794(k),k=1..n) ; end: seq(A162796(n),n=1..120) ; # R. J. Mathar, Sep 27 2009
  • Mathematica
    terms = 100;
    Cases[Import["https://oeis.org/A139251/b139251.txt", "Table"], {, }][[;; 2terms;; 2, 2]] // Accumulate (* Jean-François Alcover, Mar 24 2020 *)

Extensions

Extended by R. J. Mathar, Sep 27 2009

A162793 Number of toothpicks added to the toothpick structure A139250 at the n-th odd round.

Original entry on oeis.org

1, 4, 4, 12, 4, 12, 16, 32, 4, 12, 16, 32, 16, 36, 60, 80, 4, 12, 16, 32, 16, 36, 60, 80, 16, 36, 60, 84, 60, 112, 208, 192, 4, 12, 16, 32, 16, 36, 60, 80, 16, 36, 60, 84, 60, 112, 208, 192, 16, 36, 60, 84, 60, 112, 208, 196, 60, 112, 208, 224, 212, 364, 672, 448, 4, 12, 16, 32, 16
Offset: 1

Views

Author

Omar E. Pol, Jul 14 2009

Keywords

Comments

Bisection of A139251.
Note that these toothpicks are parallel to the initial toothpick in the structure.
First differences of A162795. - Omar E. Pol, Feb 23 2015

Examples

			From _Omar E. Pol_, Feb 23 2015: (Start)
Written as an irregular triangle in which the row lengths are the terms of A011782, the sequence begins:
1;
4;
4,12;
4,12,16,32;
4,12,16,32,16,36,60,80;
4,12,16,32,16,36,60,80,16,36,60,84,60,112,208,192;
4,12,16,32,16,36,60,80,16,36,60,84,60,112,208,192,16,36,60,84,60,112,208,196,60,112,208,224,212,364,672,448;
...
It appears that right border gives the positive terms of A001787.
It appears that row sums give A000302.
(End)
		

Crossrefs

Extensions

More terms from N. J. A. Sloane, Dec 28 2009

A162794 Number of toothpicks added to the toothpick structure A139250 at the n-th even round.

Original entry on oeis.org

0, 2, 4, 8, 8, 8, 12, 28, 16, 8, 12, 28, 20, 28, 40, 88, 32, 8, 12, 28, 20, 28, 40, 88, 36, 28, 40, 88, 56, 92, 140, 256, 64, 8, 12, 28, 20, 28, 40, 88, 36, 28, 40, 88, 56, 92, 140, 256, 68, 28, 40, 88, 56, 92, 140, 256, 88, 92, 140, 260, 172, 296, 488, 704, 128, 8, 12, 28, 20, 28
Offset: 0

Views

Author

Omar E. Pol, Jul 14 2009

Keywords

Comments

Note that these toothpicks are orthogonal to the initial toothpick in the sieve.
A bisection of A139251.

Crossrefs

Extensions

Extended by R. J. Mathar, Sep 27 2009

A194800 Number of grid points that are covered after n-th stage of A139250, assuming the vertical toothpicks have length 2 and the horizontal toothpicks have length 4.

Original entry on oeis.org

0, 3, 11, 17, 31, 39, 67
Offset: 0

Views

Author

Omar E. Pol, Sep 07 2011

Keywords

Comments

There are an infinite family of these sequences since A139250 gives the number of toothpicks in the structure regardless of the length difference between horizontal toothpicks and vertical toothpicks. Examples: A147614, this sequence, A194802, A160420, etc.

Examples

			a(2) = 11.
o o o o o
. . o . .
o o o o o
		

Crossrefs

A194802 Number of grid points that are covered after n-th stage of A139250, assuming the vertical toothpicks have length 4 and the horizontal toothpicks have length 2.

Original entry on oeis.org

0, 5, 9, 23, 29, 45, 57
Offset: 0

Views

Author

Omar E. Pol, Sep 07 2011

Keywords

Comments

There are an infinite family of these sequences since A139250 gives the number of toothpicks in the structure regardless of the length difference between horizontal toothpicks and vertical toothpicks. Examples: A147614, A194800, this sequence, A160420, etc.

Examples

			a(2) = 9.
o o o
. o .
. o .
. o .
o o o
		

Crossrefs

A163094 a(n) = A162796(n)/2.

Original entry on oeis.org

0, 1, 3, 7, 11, 15, 21, 35, 43, 47, 53, 67, 77, 91, 111, 155, 171, 175, 181, 195, 205, 219, 239, 283, 301, 315, 335, 379, 407, 453, 523, 651, 683, 687, 693, 707, 717, 731, 751, 795, 813, 827, 847, 891, 919, 965, 1035, 1163, 1197, 1211, 1231, 1275, 1303, 1349, 1419
Offset: 0

Views

Author

Omar E. Pol, Jul 28 2009

Keywords

Crossrefs

Extensions

a(0) prepended by and more terms from Jinyuan Wang, Mar 15 2020
Showing 1-8 of 8 results.