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.

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A087752 Powers of 49.

Original entry on oeis.org

1, 49, 2401, 117649, 5764801, 282475249, 13841287201, 678223072849, 33232930569601, 1628413597910449, 79792266297612001, 3909821048582988049, 191581231380566414401, 9387480337647754305649, 459986536544739960976801, 22539340290692258087863249, 1104427674243920646305299201
Offset: 0

Views

Author

Douglas Winston (douglas.winston(AT)srupc.com), Oct 02 2003

Keywords

Comments

Same as Pisot sequences E(1, 49), L(1, 49), P(1, 49), T(1, 49). Essentially same as Pisot sequences E(49, 2401), L(49, 2401), P(49, 2401), T(49, 2401). See A008776 for definitions of Pisot sequences.
The compositions of n in which each natural number is colored by one of p different colors are called p-colored compositions of n. For n >= 1, a(n) equals the number of 49-colored compositions of n such that no adjacent parts have the same color. - Milan Janjic, Nov 17 2011

Crossrefs

Bisection of A000420.
Cf. A001018 (powers of 8), ..., A001029 (powers of 19), A009964 (powers of 20), ..., A009992 (powers of 48).

Programs

Formula

G.f.: 1/(1-49*x). - Philippe Deléham, Nov 24 2008
From Vincenzo Librandi, Nov 21 2010: (Start)
a(n) = 49^n.
a(n) = 49*a(n-1), a(0)=1. (End)
From Elmo R. Oliveira, Jul 08 2025: (Start)
E.g.f.: exp(49*x).
a(n) = A000420(A005843(n)). (End)

Extensions

Edited by M. F. Hasler, Apr 19 2015

A223480 T(n,k)=Rolling icosahedron face footprints: number of nXk 0..19 arrays starting with 0 where 0..19 label faces of an icosahedron and every array movement to a horizontal or antidiagonal neighbor moves across an icosahedral edge.

Original entry on oeis.org

1, 3, 20, 9, 27, 400, 27, 135, 243, 8000, 81, 675, 2025, 2187, 160000, 243, 3375, 16875, 30375, 19683, 3200000, 729, 16875, 147825, 421875, 455625, 177147, 64000000, 2187, 84375, 1296675, 6526575, 10546875, 6834375, 1594323, 1280000000, 6561, 421875
Offset: 1

Views

Author

R. H. Hardin Mar 20 2013

Keywords

Comments

Table starts
..........1........3..........9...........27.............81..............243
.........20.......27........135..........675...........3375............16875
........400......243.......2025........16875.........147825..........1296675
.......8000.....2187......30375.......421875........6526575........101331675
.....160000....19683.....455625.....10546875......288507825.......7939566675
....3200000...177147....6834375....263671875....12755926575.....622332801675
...64000000..1594323..102515625...6591796875...563999907825...48783753036675
.1280000000.14348907.1537734375.164794921875.24937217326575.3824122400271675

Examples

			Some solutions for n=3 k=4
..0..1..6.10....0..1..4..1....0..1..0..1....0..2..8.13....0..2..8..9
..6..1..6..1....6..1..4..3....4..1..0..5....0..2..8..2....8..9..8..9
..4..1..4..3....4.17..4.17....0..5..9..5....8..2..3..4....8..2..8..9
Face neighbors:
0 -> 1 2 5
1 -> 0 4 6
2 -> 0 3 8
3 -> 2 4 16
4 -> 3 1 17
5 -> 0 7 9
6 -> 1 7 10
7 -> 6 5 11
8 -> 2 9 13
9 -> 8 5 14
10 -> 6 12 17
11 -> 7 12 14
12 -> 11 10 19
13 -> 8 15 16
14 -> 9 11 15
15 -> 14 13 19
16 -> 3 13 18
17 -> 4 10 18
18 -> 16 17 19
19 -> 15 18 12
		

Crossrefs

Column 1 is A009964(n-1)
Column 2 is A013708(n-1)
Column 3 is 9*15^(n-1)
Column 4 is 27*25^(n-1)
Row 1 is A000244(n-1)
Row 2 is 27*5^(n-2) for n>1

Formula

Empirical for column k:
k=1: a(n) = 20*a(n-1)
k=2: a(n) = 9*a(n-1)
k=3: a(n) = 15*a(n-1)
k=4: a(n) = 25*a(n-1)
k=5: a(n) = 51*a(n-1) -300*a(n-2)
k=6: a(n) = 101*a(n-1) -1900*a(n-2) +10000*a(n-3)
k=7: a(n) = 227*a(n-1) -14764*a(n-2) +411840*a(n-3) -5347200*a(n-4) +29600000*a(n-5) -48000000*a(n-6)
Empirical for row n:
n=1: a(n) = 3*a(n-1)
n=2: a(n) = 5*a(n-1) for n>2
n=3: a(n) = 9*a(n-1) -2*a(n-2) for n>4
n=4: a(n) = 17*a(n-1) -16*a(n-2) -76*a(n-3) +64*a(n-4) for n>7
n=5: a(n) = 33*a(n-1) -86*a(n-2) -1564*a(n-3) +7040*a(n-4) -6480*a(n-5) -5088*a(n-6) +5824*a(n-7) -512*a(n-8) for n>13
n=6: [order 20] for n>25

A359452 Number of vertices in the partite set of the n-Menger sponge graph that contains the corners.

Original entry on oeis.org

1, 8, 208, 3968, 80128, 1599488, 32002048, 639991808, 12800032768, 255999868928, 5120000524288, 102399997902848, 2048000008388608, 40959999966445568, 819200000134217728, 16383999999463129088, 327680000002147483648, 6553599999991410065408, 131072000000034359738368
Offset: 0

Views

Author

Allan Bickle, Jan 02 2023

Keywords

Comments

This sequence and the sequence counting the non-corner vertices (A359453) alternate as to which is larger.

Examples

			The level 1 Menger sponge graph can be formed by subdividing every edge of a cube graph.  This produces a graph with 8 corner vertices and 12 non-corner vertices, so a(1) = 8.
		

Crossrefs

Cf. A009964 (number of vertices), A291066 (number of edges).
Cf. A359453 (number of non-corner vertices).
Cf. A291066, A083233, and A332705 on the surface area of the n-Menger sponge graph.
Cf. A262710.

Programs

Formula

a(n) = (20^n + (-4)^n)/2.
a(n) = (A009964(n) + A262710(n))/2.
a(n) = 20^n - A359453(n).
From Stefano Spezia, Jan 02 2023: (Start)
O.g.f.: (1 - 8*x)/((1 - 20*x)*(1 + 4*x)).
E.g.f.: exp(8*x)*cosh(12*x). (End)

A359453 Number of vertices in the partite set of the n-Menger sponge graph that do not contain the corners.

Original entry on oeis.org

0, 12, 192, 4032, 79872, 1600512, 31997952, 640008192, 12799967232, 256000131072, 5119999475712, 102400002097152, 2047999991611392, 40960000033554432, 819199999865782272, 16384000000536870912, 327679999997852516352, 6553600000008589934592, 131071999999965640261632
Offset: 0

Views

Author

Allan Bickle, Jan 02 2023

Keywords

Comments

This sequence and the sequence counting the corner vertices (A359452) alternate as to which is larger.

Examples

			The level 1 Menger sponge graph can be formed by subdividing every edge of a cube graph.  This produces a graph with 8 corner vertices and 12 non-corner vertices, so a(1) = 12.
		

Crossrefs

Cf. A009964 (number of vertices), A291066 (number of edges).
Cf. A359452 (number of corner vertices).
Cf. A291066, A083233, and A332705 on the surface area of the n-Menger sponge graph.

Programs

Formula

a(n) = (20^n - (-4)^n)/2.
a(n) = (A009964(n) - A262710(n))/2.
a(n) = 20^n - A359452(n).
From Stefano Spezia, Jan 02 2023: (Start)
O.g.f.: 12*x/((1 - 20*x)*(1 + 4*x)).
E.g.f.: (cosh(8*x) + sinh(8*x))*sinh(12*x). (End)

A365606 Number of degree 2 vertices in the n-Sierpinski carpet graph.

Original entry on oeis.org

8, 20, 84, 500, 3540, 26996, 212052, 1684724, 13442772, 107437172, 859182420, 6872514548, 54977282004, 439809752948, 3518452514388, 28147543587572, 225180119118036, 1801440264196724, 14411520047331156, 115292154179921396, 922337214843187668, 7378697662956950900, 59029581136289955924
Offset: 1

Views

Author

Allan Bickle, Sep 12 2023

Keywords

Comments

The level 0 Sierpinski carpet graph is a single vertex. The level n Sierpinski carpet graph is formed from 8 copies of level n-1 by joining boundary vertices between adjacent copies.

Examples

			The level 1 Sierpinski carpet graph is an 8-cycle, which has 8 degree 2 vertices and 0 degree 3 or 4 vertices.  Thus a(1) = 8.
		

Crossrefs

Cf. A001018 (order), A271939 (size).
Cf. A365606 (degree 2), A365607 (degree 3), A365608 (degree 4).
Cf. A009964, A291066, A359452, A359453, A291066, A083233, A332705 (Menger sponge graph).

Programs

  • Mathematica
    LinearRecurrence[{12,-35,24},{8,20,84},30] (* Paolo Xausa, Oct 16 2023 *)
  • Python
    def A365606(n): return ((1<<3*n-1)+(3**(n-1)<<4))//5+4 # Chai Wah Wu, Nov 27 2023

Formula

a(n) = (1/10)*8^n + (16/15)*3^n + 4.
a(n) = 8*a(n-1) - 16*3^(n-2) - 28.
a(n) = 8^n - A365607(n) - A365608(n).
2*a(n) = 2*A271939(n) - 3*A365607(n) - 4*A365608(n).
G.f.: 4*x*(2 - 19*x + 31*x^2)/((1 - x)*(1 - 3*x)*(1 - 8*x)). - Stefano Spezia, Sep 12 2023

A365607 Number of degree 3 vertices in the n-Sierpinski carpet graph.

Original entry on oeis.org

0, 40, 328, 2536, 19912, 158056, 1260616, 10073320, 80551624, 644308072, 5154149704, 41232252904, 329855188936, 2638833008488, 21110638558792, 168885031942888, 1351080025960648, 10808639518937704, 86469114085259080, 691752906483344872, 5534023233270575560, 44272185810376054120
Offset: 1

Views

Author

Allan Bickle, Sep 12 2023

Keywords

Comments

The level 0 Sierpinski carpet graph is a single vertex. The level n Sierpinski carpet graph is formed from 8 copies of level n-1 by joining boundary vertices between adjacent copies.

Examples

			The level 1 Sierpinski carpet graph is an 8-cycle, which has 8 degree 2 vertices and 0 degree 3 or 4 vertices.  Thus a(1) = 0.
		

Crossrefs

Cf. A001018 (order), A271939 (size).
Cf. A365606 (degree 2), A365607 (degree 3), A365608 (degree 4).
Cf. A009964, A291066, A359452, A359453, A291066, A083233, A332705 (Menger sponge graph).

Programs

  • Mathematica
    LinearRecurrence[{12,-35,24},{0,40,328},30] (* Paolo Xausa, Oct 16 2023 *)
  • Python
    def A365607(n): return ((3<<3*n)+(3**(n-1)<<4))//5-8 # Chai Wah Wu, Nov 27 2023

Formula

a(n) = (3/5)*8^n + (16/15)*3^n - 8.
a(n) = 8*a(n-1) - 16*3^(n-2) + 56.
a(n) = 8^n - A365606(n) - A365608(n).
3*a(n) = 2*A271939(n) - 2*A365606(n) - 4*A365608(n).
G.f.: 8*x^2*(5 - 19*x)/((1 - x)*(1 - 3*x)*(1 - 8*x)). - Stefano Spezia, Sep 12 2023

A365608 Number of degree 4 vertices in the n-Sierpinski carpet graph.

Original entry on oeis.org

0, 4, 100, 1060, 9316, 77092, 624484, 5019172, 40223332, 321996580, 2576602468, 20614709284, 164923342948, 1319403749668, 10555281015652, 84442401180196, 675539668606564, 5404318726347556, 43234553943265636, 345876443943580708, 2767011588741012580, 22136092821505201444, 177088742906772914020
Offset: 1

Views

Author

Allan Bickle, Sep 12 2023

Keywords

Comments

The level 0 Sierpinski carpet graph is a single vertex. The level n Sierpinski carpet graph is formed from 8 copies of level n-1 by joining boundary vertices between adjacent copies.

Examples

			The level 1 Sierpinski carpet graph is an 8-cycle, which has 8 degree 2 vertices and 0 degree 3 or 4 vertices.  Thus a(1) = 0.
		

Crossrefs

Cf. A001018 (order), A271939 (size).
Cf. A365606 (degree 2), A365607 (degree 3), A365608 (degree 4).
Cf. A009964, A291066, A359452, A359453, A291066, A083233, A332705 (Menger sponge graph).

Programs

  • Mathematica
    LinearRecurrence[{12,-35,24},{0,4,100},30] (* Paolo Xausa, Oct 16 2023 *)
  • Python
    def A365608(n): return ((3<<3*n-1)-(3**(n-1)<<5))//5+4 # Chai Wah Wu, Nov 27 2023

Formula

a(n) = (3/10)*8^n - (32/15)*3^n + 4.
a(n) = 8*a(n-1) + 32*3^(n-2) - 28.
a(n) = 8^n - A365606(n) - A365607(n).
4*a(n) = 2*A271939(n) - 2*A365606(n) - 3*A365607(n).
G.f.: 4*x^2*(1 + 13*x)/((1 - x)*(1 - 3*x)*(1 - 8*x)). - Stefano Spezia, Sep 12 2023

A367700 Number of degree 2 vertices in the n-Menger sponge graph.

Original entry on oeis.org

12, 72, 744, 11256, 201960, 3871416, 76138536, 1512609912, 30171384168, 602782587960, 12050495247528, 240968665611768, 4819043435788776, 96378229818994104, 1927543485550004520, 38550700825394191224, 771012665426135994984, 15420242499878035355448, 308404763528431125030312
Offset: 1

Views

Author

Allan Bickle, Nov 27 2023

Keywords

Comments

The level 0 Menger sponge graph is a single vertex. The level n Menger sponge graph is formed from 20 copies of level n-1 in the shape of a cube with middle faces removed by joining boundary vertices between adjacent copies.

Examples

			The level 1 Menger sponge graph is a cube with each edge subdivided, which has 12 degree 2 vertices and 8 degree 3 vertices.  Thus a(1) = 12.
		

Crossrefs

Cf. A009964 (number of vertices), A291066 (number of edges).
Cf. A359452, A359453 (numbers of corner and non-corner vertices).
Cf. A083233, A332705 (surface area).
Cf. A367701, A367702, A367706, A367707 (degrees 2 through 6).
Cf. A001018, A271939, A365602, A365606, A365607, A365608 (Sierpinski carpet graphs).

Programs

  • Mathematica
    LinearRecurrence[{31,-244,480}, {12, 72, 744}, 25] (* Paolo Xausa, Nov 28 2023 *)
  • Python
    def A367700(n): return (5*20**n+(34<<3*n)+216*3**n)//85 # Chai Wah Wu, Nov 27 2023

Formula

a(n) = (1/17)*20^n + (2/5)*8^n + (216/85)*3^n.
a(n) = 20*a(n-1) - (3/5)*8^n - (72/5)*3^n.
a(n) = 20^n - A367701(n) - A367702(n) - A367706(n) - A367707(n).
2*a(n) = 2*A291066(n) - 3*A367701(n) - 4*A365602(n) - 5*A367706(n) - 6*A367707(n).
G.f.: 12*x*(1 - 25*x + 120*x^2)/((1 - 3*x)*(1 - 8*x)*(1 - 20*x)). - Stefano Spezia, Nov 27 2023

A367701 Number of degree 3 vertices in the n-Menger sponge graph.

Original entry on oeis.org

8, 152, 2744, 49688, 941624, 18381464, 363917240, 7248334616, 144725667128, 2892582307736, 57836189374136, 1156600107729944, 23131012640050232, 462612336455034008, 9252183397644168632, 185043161299165038872, 3700859172747355380536, 74017151029040948253080
Offset: 1

Views

Author

Allan Bickle, Nov 27 2023

Keywords

Comments

The level 0 Menger sponge graph is a single vertex. The level n Menger sponge graph is formed from 20 copies of level n-1 in the shape of a cube with middle faces removed by joining boundary vertices between adjacent copies.

Examples

			The level 1 Menger sponge graph is a cube with each edge subdivided, which has 12 degree 2 vertices and 8 degree 3 vertices.  Thus a(1) = 8.
		

Crossrefs

Cf. A009964 (number of vertices), A291066 (number of edges).
Cf. A359452, A359453 (numbers of corner and non-corner vertices).
Cf. A291066, A083233, A332705 (surface area).
Cf. A367700, A367701, A367702, A367706, A367707 (degrees 2 through 6).
Cf. A001018, A271939, A365606, A365607, A365608 (Sierpinski carpet graphs).

Programs

  • Mathematica
    LinearRecurrence[{32,-275,724,-480},{8,152,2744,49688},25] (* Paolo Xausa, Nov 28 2023 *)
  • Python
    def A367701(n): return ((3*5**n<<(n<<1)+3)+(51<<(3*n+1))-(3**(n+3)<<4))//85+8 # Chai Wah Wu, Nov 28 2023

Formula

a(n) = (24/85)*20^n + (6/5)*8^n - (432/85)*3^n + 8.
a(n) = 20*a(n-1) - (9/5)*8^n + (144/5)*3^n - 152.
a(n) = 20^n - A367700(n) - A367702(n) - A367706(n) - A367707(n).
3*a(n) = 2*A291066(n) - 2*A367700(n) - 4*A365602(n) - 5*A367706(n) - 6*A367707(n).
G.f.: 8*x*(1 - 13*x + 10*x^2 - 264*x^3)/((1 - x)*(1 - 3*x)*(1 - 8*x)*(1 - 20*x)). - Stefano Spezia, Nov 27 2023

A367702 Number of degree 4 vertices in the n-Menger sponge graph.

Original entry on oeis.org

0, 144, 2784, 57552, 1180320, 23889936, 480221280, 9624275280, 192645717024, 3854200280208, 77094305873376, 1541968557881808, 30840030795738528, 616805893363960080, 12336160087905835872, 246723539526229152336, 4934473492678780614432, 98689491470837087102352
Offset: 1

Views

Author

Allan Bickle, Nov 27 2023

Keywords

Comments

The level 0 Menger sponge graph is a single vertex. The level n Menger sponge graph is formed from 20 copies of level n-1 in the shape of a cube with middle faces removed by joining boundary vertices between adjacent copies.

Examples

			The level 1 Menger sponge graph is a cube with each edge subdivided, which has 12 degree 2 vertices and 8 degree 3 vertices.  Thus a(1) = 0.
		

Crossrefs

Cf. A009964 (number of vertices), A291066 (number of edges).
Cf. A359452, A359453 (numbers of corner and non-corner vertices).
Cf. A291066, A083233, A332705 (surface area).
Cf. A367700, A367701, A367702, A367706, A367707 (degrees 2 through 6).
Cf. A001018, A271939, A365606, A365607, A365608 (Sierpinski carpet graphs).

Programs

  • Mathematica
    LinearRecurrence[{32,-275,724,-480},{0,144,2784,57552},25] (* Paolo Xausa, Nov 29 2023 *)
  • Python
    def A367702(n): return ((5**n<<(n<<1)+5)-(17<<(3*n+2))+(3**(n+4)<<3))//85-24 # Chai Wah Wu, Nov 28 2023

Formula

a(n) = (32/85)*20^n - (4/5)*8^n + (648/85)*3^n - 24.
a(n) = 20*a(n-1) + (6/5)*8^n - (216/5)*3^n + 456.
a(n) = 20^n - A367700(n) - A367701(n) - A367706(n) - A367707(n).
4*a(n) = 2*A291066(n) - 2*A367700(n) - 3*A367701(n) - 5*A367706(n) - 6*A367707(n).
G.f.: 12*x^2*(7 - 224*x + 1865*x^2 - 4308*x^3)/(5*(1 - x)*(1 - 3*x)*(1 - 8*x)*(1 - 20*x)). - Stefano Spezia, Nov 28 2023
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