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.

A170886 Similar to A160406, but always staying outside the wedge, starting at stage 1 with a toothpick whose midpoint touches the vertex of the wedge.

Original entry on oeis.org

0, 1, 3, 5, 7, 11, 17, 23, 29, 37, 49, 55, 63, 75, 93, 107, 121, 141, 161, 167, 175, 187, 205, 219, 235, 259, 285, 301, 325, 363, 409, 447, 489, 541, 577, 583, 591, 603, 621, 635, 651, 675, 701, 717, 741, 779, 825, 863, 907, 963, 1005, 1021, 1045, 1083, 1129
Offset: 0

Views

Author

Omar E. Pol, Jan 09 2010

Keywords

Comments

See A170887 for the first differences.

Crossrefs

Extensions

Terms beyond a(9) from R. J. Mathar, Jan 25 2010

A170893 First differences of the toothpick sequence A170892.

Original entry on oeis.org

0, 1, 1, 2, 4, 4, 4, 8, 10, 10, 4, 8, 10, 12, 12, 22, 26, 18, 4, 8, 10, 12, 12, 22, 26, 20, 12, 22, 28, 32, 42, 66, 66, 34, 4, 8, 10, 12, 12, 22, 26, 20, 12, 22, 28, 32, 42, 66, 66, 36, 12, 22, 28, 32, 42, 66, 68, 48, 42, 68, 84, 102, 146, 194, 162, 66, 4, 8, 10, 12, 12, 22, 26, 20, 12, 22, 28, 32, 42, 66, 66, 36, 12, 22, 28, 32, 42, 66, 68, 48, 42, 68, 84
Offset: 0

Views

Author

Omar E. Pol, Jan 09 2010

Keywords

Comments

This describes how many toothpicks are added at each step (as to form the upper bar of a T) at all "exposed" endpoints, starting from an initial configuration with a vertical toothpick whose lower endpoint rests on the top of the conic region { (x,y): y < -|x| } into which the toothpicks may not extend. - M. F. Hasler, Jan 30 2013

Examples

			From _Omar E. Pol_, Jan 30 2013 (Start):
If written as an irregular triangle in which rows 0..2 have length 1, it appears that row j has length 2^(j-3), if j >= 3.
0;
1;
1;
2;
4,4;
4,8,10,10;
4,8,10,12,12,22,26,18;
4,8,10,12,12,22,26,20,12,22,28,32,42,66,66,34;
4,8,10,12,12,22,26,20,12,22,28,32,42,66,66,36,12,22,28,32,42,66,68,48,42,68,84,102,146,194,162,66;
4,8,10,12,12,22,26,20,12,22,28,32,42,66,66,36,12,22,28,32,42,66,68,48,42,68,84,...
(End)
		

Crossrefs

Programs

  • PARI
    A170893(n, print_all=0)={my( ee=[[2*I, I]], p=Set( concat( vector( 2*n-(n>0), k, k-n-abs(k-n)*I ), I ))); print_all & print1("1,1"); for(i=3, n, p=setunion(p, Set(Mat(ee~)[, 1])); my(c, d, ne=[]); for( k=1, #ee, setsearch(p, c=ee[k][1]+d=ee[k][2]*I) || ne=setunion(ne, Set([[c, d]])); setsearch(p, c-2*d) || ne=setunion(ne, Set([[c-2*d, -d]]))); forstep( k=#ee=eval(ne), 2, -1, ee[k][1]==ee[k-1][1] & k-- & ee=vecextract(ee, Str("^"k"..", k+1))); print_all & print1(","#ee)); (n>0)*#ee} \\ M. F. Hasler, Jan 30 2013

Extensions

Values beyond a(10) from M. F. Hasler, Jan 30 2013

A170889 First differences of toothpick sequence A170888.

Original entry on oeis.org

0, 1, 2, 4, 4, 4, 6, 10, 8, 4, 6, 10, 10, 12, 20, 26, 16, 4, 6, 10, 10, 12, 20, 26, 18, 12, 20, 28, 30, 42, 64, 66, 32, 4, 6, 10, 10, 12, 20, 26, 18, 12, 20, 28, 30, 42, 64, 66, 34, 12, 20, 28, 30, 42, 64, 68, 46, 42, 66, 84, 100, 146, 192, 162, 64, 4, 6, 10, 10, 12, 20, 26, 18, 12
Offset: 0

Views

Author

Omar E. Pol, Jan 09 2010

Keywords

Examples

			From _Omar E. Pol_, Jan 30 2013 (Start):
Written as an irregular triangle:
0;
1;
2;
4,4;
4,6,10,8;
4,6,10,10,12,20,26,16;
4,6,10,10,12,20,26,18,12,20,28,30,42,64,66,32;
4,6,10,10,12,20,26,18,12,20,28,30,42,64,66,34,12,20,28,30,42,64,68,46,42,66,84,100,146,192,162,64;
(End)
		

Crossrefs

Extensions

Terms beyond a(10) from R. J. Mathar, Jan 25 2010

A170891 First differences of the toothpick sequence A170890.

Original entry on oeis.org

0, 1, 1, 2, 3, 3, 4, 7, 8, 8, 6, 10, 8, 10, 12, 20, 20, 16, 12, 14, 8, 10, 12, 20, 20, 18, 18, 24, 22, 28, 40, 56, 52, 38, 28, 22, 8, 10, 12, 20, 20, 18, 18, 24, 22, 28, 40, 56, 52, 40, 34, 32, 22, 28, 40, 56, 54, 50, 56, 66, 68, 92, 132, 160, 138, 98, 68, 38
Offset: 0

Views

Author

Omar E. Pol, Jan 09 2010

Keywords

Comments

Number of toothpicks added at n-th stage to the toothpick structure of A170890. - Omar E. Pol, Jan 31 2013

Examples

			From _Omar E. Pol_, Jan 31 2013 (Start):
If written as an irregular triangle in which rows 0..4 have length 1, it appears that row j has length 2^(j-5), if j >= 5.
0;
1;
1;
2;
3;
3;
4,7;
8,8,6,10;
8,10,12,20,20,16,12,14;
8,10,12,20,20,18,18,24,22,28,40,56,52,38,28,22;
8,10,12,20,20,18,18,24,22,28,40,56,52,40,34,32,22,28,40,56,54,50,56,66,68,92,132,160,138,98,68,38;
(End)
		

Crossrefs

Extensions

a(9) corrected by Omar E. Pol, following an observation by Kevin Ryde, Jan 29 2013
Terms beyond a(9) from M. F. Hasler, Jan 29 2013
Showing 1-4 of 4 results.