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 1-6 of 6 results.

A274142 Number of integers in n-th generation of tree T(1/2) defined in Comments.

Original entry on oeis.org

1, 1, 1, 2, 2, 4, 5, 8, 11, 17, 25, 37, 54, 81, 119, 177, 261, 388, 574, 851, 1260, 1868, 2767, 4101, 6077, 9006, 13347, 19781, 29315, 43448, 64392, 95436, 141444, 209636, 310705, 460501, 682519, 1011581, 1499295, 2222155, 3293534, 4881472, 7235018, 10723311, 15893460, 23556367, 34913897, 51747400
Offset: 0

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Author

Clark Kimberling, Jun 11 2016

Keywords

Comments

Let T* be the infinite tree with root 0 generated by these rules: if p is in T*, then p+1 is in T* and x*p is in T*. Let g(n) be the set of nodes in the n-th generation, so that g(0) = {0}, g(1) = {1}, g(2) = {2,x}, g(3) = {3,2x,x+1,x^2}, etc. Let T(r) be the tree obtained by substituting r for x.
Guide to related sequences:
r sequence
-1/2 A274147
-1/3 A274148
-1/4 A274149
-2/3 A274150
-3/4 A274151
-3/2 A274154
-5/2 A274155
2^(1/2) A000045 (Fibonacci numbers)
2^(1/3) A000930
2^(1/4) A003269
2^(-1/2) A274156
3^(-1/2) A274157
2^(-1/3) A274158
3^(-1/3) A274159
(-1+3i)/2 A274168

Examples

			If r = 1/2, then g(3) = {3,2r,r+1, r^2}, in which the integers are 3 and 1, so that a(3) = 2.
		

Crossrefs

Programs

  • Mathematica
    z = 18; t = Join[{{0}}, Expand[NestList[DeleteDuplicates[Flatten[Map[{# + 1, x*#} &, #], 1]] &, {1}, z]]];
    u = Table[t[[k]] /. x -> 1/2, {k, 1, z}];
    Table[Count[Map[IntegerQ, u[[k]]], True], {k, 1, z}]
    (* second program: *)
    T[0] = {0}; T[n_] := T[n] = Complement[Join[T[n-1]+1, x*T[n-1]], T[n-1]]; Reap[For[n = 0, n <= 25, n++, cnt = Count[T[n] /. x -> 1/2, Integer]; Print[n, " ", cnt]; Sow[cnt]]][[2, 1]] (* _Jean-François Alcover, Jun 14 2016 *)

Extensions

More terms from Jean-François Alcover, Jun 14 2016
More terms from Kenny Lau, Jul 04 2016

A284222 T(n,k) = Number of n X k 0..1 arrays with the number of 1's horizontally or antidiagonally adjacent to some 0 equal to the number of 0's adjacent to some 1, with top left element zero.

Original entry on oeis.org

1, 2, 2, 3, 6, 4, 6, 13, 19, 8, 10, 44, 70, 62, 16, 19, 143, 499, 467, 212, 32, 33, 495, 3214, 6511, 3224, 751, 64, 62, 1746, 22729, 85887, 91260, 23218, 2719, 128, 112, 6399, 163708, 1214427, 2417194, 1317770, 170155, 10002, 256, 212, 23776, 1209005
Offset: 1

Views

Author

R. H. Hardin, Mar 23 2017

Keywords

Comments

Table starts
...1.....2.......3..........6............10..............19.................33
...2.....6......13.........44...........143.............495...............1746
...4....19......70........499..........3214...........22729.............163708
...8....62.....467.......6511.........85887.........1214427...........17538010
..16...212....3224......91260.......2417194........68272108.........1970768869
..32...751...23218....1317770......69938626......3945536189.......227677212684
..64..2719..170155...19371893....2058141264....232036495984.....26772321109067
.128.10002.1264605..288303232...61304713234..13815034342734...3187484402643589
.256.37258.9488108.4330336770.1842647045686.830095968128023.383012404461341362

Examples

			Some solutions for n=4 k=4
..0..1..1..1. .0..1..0..1. .0..0..1..1. .0..1..1..1. .0..1..1..1
..0..0..0..1. .0..0..1..1. .1..0..0..0. .0..0..1..0. .0..0..0..1
..1..1..0..1. .0..1..0..1. .1..0..1..1. .1..1..0..1. .1..1..0..0
..0..0..1..0. .1..0..0..1. .0..1..1..1. .0..1..0..0. .1..0..1..0
		

Crossrefs

Column 1 is A000079(n-1).
Row 1 is A274160(n+1).

A284334 T(n,k) = Number of n X k 0..1 arrays with the number of 1's horizontally, diagonally or antidiagonally adjacent to some 0 equal to the number of 0's adjacent to some 1, with top left element zero.

Original entry on oeis.org

1, 2, 2, 3, 4, 4, 6, 13, 13, 8, 10, 34, 49, 42, 16, 19, 118, 373, 415, 134, 32, 33, 419, 2259, 5130, 2243, 467, 64, 62, 1481, 18114, 68458, 70039, 19385, 1689, 128, 112, 5394, 120058, 966889, 1792007, 1000935, 122495, 6210, 256, 212, 19848, 959041, 13941789
Offset: 1

Views

Author

R. H. Hardin, Mar 25 2017

Keywords

Comments

Table starts
...1.....2.......3..........6............10..............19.................33
...2.....4......13.........34...........118.............419...............1481
...4....13......49........373..........2259...........18114.............120058
...8....42.....415.......5130.........68458..........966889...........13941789
..16...134....2243......70039.......1792007........53435287.........1495300322
..32...467...19385....1000935......53977741......3063494246.......177476886878
..64..1689..122495...14581112....1544903012....179138039472.....20513380740103
.128..6210.1021999..215806808...46769835006..10629901713799...2467754689139967
.256.23178.7013557.3229703988.1390664014686.637390912071364.294625135884008616

Examples

			Some solutions for n=4, k=4
..0..0..0..0. .0..1..0..1. .0..0..1..1. .0..1..1..0. .0..0..1..0
..1..0..1..0. .1..0..1..1. .0..1..1..0. .1..0..0..1. .0..1..0..1
..1..0..0..0. .0..1..0..1. .1..1..1..0. .1..1..0..0. .1..0..1..1
..1..1..1..1. .0..0..1..0. .0..0..1..1. .0..1..1..0. .0..0..1..1
		

Crossrefs

Column 1 is A000079(n-1).
Column 2 is A284159.
Row 1 is A274160(n+1).

A284113 T(n,k) = Number of n X k 0..1 arrays with the number of 1's king-move adjacent to some 0 equal to the number of 0's adjacent to some 1, with top left element zero.

Original entry on oeis.org

1, 2, 2, 3, 4, 3, 6, 13, 13, 6, 10, 46, 25, 46, 10, 19, 160, 435, 435, 160, 19, 33, 571, 1230, 5896, 1230, 571, 33, 62, 2095, 20275, 80200, 80200, 20275, 2095, 62, 112, 7802, 67957, 1143533, 905327, 1143533, 67957, 7802, 112, 212, 29326, 1057769, 16442183
Offset: 1

Views

Author

R. H. Hardin, Mar 20 2017

Keywords

Comments

Table starts
...1......2........3...........6.............10................19
...2......4.......13..........46............160...............571
...3.....13.......25.........435...........1230.............20275
...6.....46......435........5896..........80200...........1143533
..10....160.....1230.......80200.........905327..........61595318
..19....571....20275.....1143533.......61595318........3514396333
..33...2095....67957....16442183......835390074......202053817163
..62...7802..1057769...240146980....51786529350....11804599876991
.112..29326..4091201..3538905880...809052347723...696189477669561
.212.111040.57977326.52568393480.45439256969227.41397421665690592

Examples

			Some solutions for n=4, k=4
..0..0..0..1. .0..1..1..1. .0..0..0..0. .0..0..0..0. .0..0..1..0
..1..1..1..1. .1..1..0..1. .1..0..1..0. .0..1..1..1. .1..1..1..0
..1..0..0..1. .1..0..0..0. .1..1..1..1. .0..1..1..1. .0..1..1..0
..0..0..1..0. .0..0..0..1. .1..1..1..0. .1..0..1..0. .1..1..0..0
		

Crossrefs

Column 1 is A274160(n+1).

A284165 T(n,k) = Number of n X k 0..1 arrays with the number of 1's horizontally or vertically adjacent to some 0 equal to the number of 0's adjacent to some 1, with top left element zero.

Original entry on oeis.org

1, 2, 2, 3, 4, 3, 6, 13, 13, 6, 10, 42, 62, 42, 10, 19, 134, 461, 461, 134, 19, 33, 467, 2872, 5888, 2872, 467, 33, 62, 1689, 21790, 80072, 80072, 21790, 1689, 62, 112, 6210, 154108, 1142173, 2179255, 1142173, 154108, 6210, 112, 212, 23178, 1174235
Offset: 1

Views

Author

R. H. Hardin, Mar 21 2017

Keywords

Comments

Table starts
...1.....2.......3..........6............10..............19.................33
...2.....4......13.........42...........134.............467...............1689
...3....13......62........461..........2872...........21790.............154108
...6....42.....461.......5888.........80072.........1142173...........16699997
..10...134....2872......80072.......2179255........63520018.........1852406216
..19...467...21790....1142173......63520018......3648835932.......213897742464
..33..1689..154108...16699997....1852406216....213897742464.....25064817057781
..62..6210.1174235..247899694...55270158210..12712253739523...2981736353245523
.112.23178.8682209.3717494360.1656400271264.762954434250117.357844048109256955

Examples

			Some solutions for n=4, k=4
..0..1..0..1. .0..0..0..1. .0..0..0..1. .0..0..0..1. .0..1..1..0
..0..0..0..1. .1..0..0..1. .0..1..1..1. .0..1..1..1. .1..0..1..0
..1..1..0..1. .1..0..1..1. .0..1..1..1. .0..0..1..1. .0..1..1..0
..0..1..0..1. .0..1..1..1. .0..0..0..1. .1..0..1..1. .0..1..0..1
		

Crossrefs

Column 1 is A274160(n+1).

A284199 T(n,k) = Number of n X k 0..1 arrays with the number of 1's horizontally, antidiagonally or vertically adjacent to some 0 equal to the number of 0's adjacent to some 1, with top left element zero.

Original entry on oeis.org

1, 2, 2, 3, 4, 3, 6, 13, 13, 6, 10, 40, 43, 40, 10, 19, 131, 412, 412, 131, 19, 33, 455, 1919, 5268, 1919, 455, 33, 62, 1611, 18842, 71181, 71181, 18842, 1611, 62, 112, 5818, 105367, 1001047, 1488503, 1001047, 105367, 5818, 112, 212, 21328, 983238
Offset: 1

Views

Author

R. H. Hardin, Mar 22 2017

Keywords

Comments

Table starts
...1.....2.......3..........6............10..............19.................33
...2.....4......13.........40...........131.............455...............1611
...3....13......43........412..........1919...........18842.............105367
...6....40.....412.......5268.........71181.........1001047...........14392557
..10...131....1919......71181.......1488503........54333131.........1321614728
..19...455...18842....1001047......54333131......3083244672.......178138187113
..33..1611..105367...14392557....1321614728....178138187113.....18564422929880
..62..5818..983238..210449237...45952259333..10468760423253...2429325477564655
.112.21328.6123441.3113715736.1219757876905.622301968698475.271315506003954612

Examples

			Some solutions for n=4, k=4
..0..1..1..0. .0..1..0..0. .0..1..1..0. .0..1..1..0. .0..0..0..0
..1..0..1..0. .1..0..0..1. .1..0..1..1. .1..0..0..1. .0..0..0..0
..1..0..0..1. .1..0..0..1. .0..1..1..0. .1..0..0..0. .0..0..1..1
..1..0..0..1. .1..1..1..0. .0..0..1..0. .1..1..0..1. .1..1..1..0
		

Crossrefs

Column 1 is A274160(n+1).
Showing 1-6 of 6 results.