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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A101104 a(1)=1, a(2)=12, a(3)=23, and a(n)=24 for n>=4.

Original entry on oeis.org

1, 12, 23, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24
Offset: 1

Views

Author

Cecilia Rossiter, Dec 15 2004

Keywords

Comments

Original name: The first summation of row 4 of Euler's triangle - a row that will recursively accumulate to the power of 4.

Crossrefs

For other sequences based upon MagicNKZ(n,k,z):
..... | n = 1 | n = 2 | n = 3 | n = 4 | n = 5 | n = 6 | n = 7
---------------------------------------------------------------------------
z = 0 | A000007 | A019590 | .......MagicNKZ(n,k,0) = A008292(n,k+1) .......
z = 1 | A000012 | A040000 | A101101 | thisSeq | A101100 | ....... | .......
z = 2 | A000027 | A005408 | A008458 | A101103 | A101095 | ....... | .......
z = 3 | A000217 | A000290 | A003215 | A005914 | A101096 | ....... | .......
z = 4 | A000292 | A000330 | A000578 | A005917 | A101098 | ....... | .......
z = 5 | A000332 | A002415 | A000537 | A000583 | A022521 | ....... | A255181
Cf. A101095 for an expanded table and more about MagicNKZ.

Programs

  • Mathematica
    MagicNKZ = Sum[(-1)^j*Binomial[n+1-z, j]*(k-j+1)^n, {j, 0, k+1}];Table[MagicNKZ, {n, 4, 4}, {z, 1, 1}, {k, 0, 34}]
    Join[{1, 12, 23},LinearRecurrence[{1},{24},56]] (* Ray Chandler, Sep 23 2015 *)

Formula

a(k) = MagicNKZ(4,k,1) where MagicNKZ(n,k,z) = Sum_{j=0..k+1} (-1)^j*binomial(n+1-z,j)*(k-j+1)^n (cf. A101095). That is, a(k) = Sum_{j=0..k+1} (-1)^j*binomial(4, j)*(k-j+1)^4.
a(1)=1, a(2)=12, a(3)=23, and a(n)=24 for n>=4. - Joerg Arndt, Nov 30 2014
G.f.: x*(1+11*x+11*x^2+x^3)/(1-x). - Colin Barker, Apr 16 2012

Extensions

New name from Joerg Arndt, Nov 30 2014
Original Formula edited and Crossrefs table added by Danny Rorabaugh, Apr 22 2015

A002299 Binomial coefficients C(2*n+5,5).

Original entry on oeis.org

1, 21, 126, 462, 1287, 3003, 6188, 11628, 20349, 33649, 53130, 80730, 118755, 169911, 237336, 324632, 435897, 575757, 749398, 962598, 1221759, 1533939, 1906884, 2349060, 2869685, 3478761, 4187106, 5006386, 5949147, 7028847, 8259888, 9657648, 11238513
Offset: 0

Views

Author

N. J. A. Sloane, Eric Lane

Keywords

Comments

Number of standard tableaux of shape (2n+1,1^5). - Emeric Deutsch, May 30 2004

Crossrefs

Programs

Formula

a(n) = A000389(2*n+5).
G.f.: (1+15*x+15*x^2+x^3)/(1-x)^6 = (1+x)*(x^2+14*x+1)/(1-x)^6.
E.g.f.: (30 + 600*x + 1275*x^2 + 730*x^3 + 140*x^4 + 8*x^5)*exp(x)/30. - G. C. Greubel, Nov 23 2017
Sum_{n>=0} (-1)^n/a(n) = 5*(10/3 - Pi). - Matthieu Pluntz, Oct 08 2019
Sum_{n>=0} 1/a(n) = 40*log(2) - 80/3. - Amiram Eldar, Jan 03 2022
From Peter Bala, Sep 03 2023: (Start)
a(n) = Sum_{0 <= i <= j <= n} (j+1)*(2*i+1)^2.
a(n) = (n+2)*(2*n+5)/(n*(2*n-1))*a(n-1) with a(0) := 1. (End)
a(n) = 2*A225007(n) - A006324(n+1). - Yasser Arath Chavez Reyes, Feb 27 2024

A054559 Number of labeled pure 2-complexes on n nodes (0-simplexes) with 5 2-simplexes and 8 1-simplexes.

Original entry on oeis.org

30, 180, 630, 1680, 3780, 7560, 13860, 23760, 38610, 60060, 90090, 131040, 185640, 257040, 348840, 465120, 610470, 790020, 1009470, 1275120, 1593900, 1973400, 2421900, 2948400, 3562650, 4275180, 5097330, 6041280, 7120080, 8347680, 9738960, 11309760, 13076910
Offset: 5

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Author

Vladeta Jovovic, Apr 10 2000

Keywords

Comments

Number of {T_1,T_2,...,T_k} where T_i,i=1..k are 3-subsets of an n-set such that {D | D is 2-subset of T_i for some i=1..k} has l elements; k=5,l=8.
Let H be the n X n Hilbert matrix H(i,j) = 1/(i+j-1) for 1 <= i,j <= n. Let B be the inverse matrix of H. The sum of the elements in row 3 of B equals -a(n+2). - T. D. Noe, May 01 2011

References

  • V. Jovovic, On the number of two-dimensional simplicial complexes (in Russian), Metody i sistemy tekhnicheskoy diagnostiki, Vypusk 16, Mezhvuzovskiy zbornik nauchnykh trudov, Izdatelstvo Saratovskogo universiteta, 1991.

Crossrefs

Programs

  • Magma
    I:=[30, 180, 630, 1680, 3780, 7560]; [n le 6 select I[n] else 6*Self(n-1)-15*Self(n-2)+20*Self(n-3)-15*Self(n-4)+6*Self(n-5)-Self(n-6): n in [1..30]]; // Vincenzo Librandi, Apr 29 2012
    
  • Mathematica
    Table[n*(n+1)*(n+2)*(n+3)*(n+4)/4, {n,1,100}] (* Vladimir Joseph Stephan Orlovsky, Jul 21 2009 *)
    CoefficientList[Series[30/(1-x)^6,{x,0,30}],x] (* Vincenzo Librandi, Apr 29 2012 *)
  • PARI
    x='x+O('x^30); Vec(serlaplace(x^5*exp(x)/4)) \\ G. C. Greubel, Nov 23 2017

Formula

a(n) = 30*C(n,5) = 30*A000389(n) = n*(n-1)*(n-2)*(n-3)*(n-4)/4.
G.f.: 30*x^5/(1-x)^6. - Colin Barker, Jan 19 2012
a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 15*a(n-4) + 6*a(n-5) - a(n-6). - Vincenzo Librandi, Apr 29 2012
E.g.f.: x^5*exp(x)/4. - G. C. Greubel, Nov 23 2017
From Amiram Eldar, Mar 08 2022: (Start)
Sum_{n>=5} 1/a(n) = 1/24.
Sum_{n>=5} (-1)^(n+1)/a(n) = 8*log(2)/3 - 131/72. (End)

A099242 (6n+5)-th terms of expansion of 1/(1 - x - x^6).

Original entry on oeis.org

1, 7, 34, 153, 686, 3088, 13917, 62721, 282646, 1273690, 5739647, 25864698, 116554700, 525233175, 2366870474, 10665883415, 48063918336, 216591552484, 976031547888, 4398313653120, 19820223058176, 89316331907533
Offset: 0

Views

Author

Paul Barry, Oct 08 2004

Keywords

Comments

A row of A099239.
Equals INVERT transform of A000389, C(n,5). [Gary W. Adamson, Feb 02 2009]

Crossrefs

Cf. A000389.

Programs

  • Mathematica
    CoefficientList[Series[1/((1 - x)^6 - x), {x, 0, 50}], x] (* G. C. Greubel, Nov 24 2017 *)
    LinearRecurrence[{7,-15,20,-15,6,-1},{1,7,34,153,686,3088},30] (* Harvey P. Dale, May 06 2018 *)
  • PARI
    my(x='x+O('x^50)); Vec(1/((1-x)^6-x)) \\ G. C. Greubel, Nov 24 2017

Formula

G.f.: 1/((1-x)^6-x).
a(n) = 7*a(n-1) - 15*a(n-2) + 20*a(n-3) - 15*a(n-4) + 6*a(n-5) - a(n-6).
a(n) = Sum_{k=0..n} binomial(6*n-5*(k-1), k).
a(n) = Sum_{k=0..n} binomial(n+5*(k+1), k+5*(k+1)).
a(n) = Sum_{k=0..n} binomial(n+5*(k+1), n-k).

A238801 Triangle T(n,k), read by rows, given by T(n,k) = C(n+1, k+1)*(1-(k mod 2)).

Original entry on oeis.org

1, 2, 0, 3, 0, 1, 4, 0, 4, 0, 5, 0, 10, 0, 1, 6, 0, 20, 0, 6, 0, 7, 0, 35, 0, 21, 0, 1, 8, 0, 56, 0, 56, 0, 8, 0, 9, 0, 84, 0, 126, 0, 36, 0, 1, 10, 0, 120, 0, 252, 0, 120, 0, 10, 0, 11, 0, 165, 0, 462, 0, 330, 0, 55, 0, 1, 12, 0, 220, 0, 792, 0, 792, 0, 220, 0, 12, 0
Offset: 0

Views

Author

Philippe Deléham, Mar 05 2014

Keywords

Comments

Row sums are powers of 2.

Examples

			Triangle begins:
1;
2, 0;
3, 0, 1;
4, 0, 4, 0;
5, 0, 10, 0, 1;
6, 0, 20, 0, 6, 0;
7, 0, 35, 0, 21, 0, 1;
8, 0, 56, 0, 56, 0, 8, 0;
9, 0, 84, 0, 126, 0, 36, 0, 1;
10, 0, 120, 0, 252, 0, 120, 0, 10, 0; etc.
		

Crossrefs

Programs

  • Mathematica
    Table[Binomial[n + 1, k + 1]*(1 - Mod[k , 2]), {n, 0, 10}, {k, 0, n}] // Flatten (* G. C. Greubel, Nov 22 2017 *)
  • PARI
    T(n,k) = binomial(n+1, k+1)*(1-(k % 2));
    tabl(nn) = for (n=0, nn, for (k=0, n, print1(T(n,k), ", ")); print); \\ Michel Marcus, Nov 23 2017

Formula

G.f.: 1/((1+(y-1)*x)*(1-(y+1)*x)).
T(n,k) = 2*T(n-1,k) + T(n-2,k-2) - T(n-2,k), T(0,0) = 1, T(1,0) = 2, T(1,1) = 0, T(n,k) = 0 if k<0 or if k>n.
Sum_{k=0..n} T(n,k)*x^k = A000027(n+1), A000079(n), A015518(n+1), A003683(n+1), A079773(n+1), A051958(n+1), A080920(n+1), A053455(n), A160958(n+1) for x = 0, 1, 2, 3, 4, 5, 6, 7, 8 respectively.

A278325 T(n,k)=Number of nXk 0..1 arrays with rows and columns in lexicographic nondecreasing order but with exactly two mistakes.

Original entry on oeis.org

0, 0, 0, 0, 3, 0, 1, 20, 20, 1, 6, 94, 236, 94, 6, 21, 395, 1678, 1678, 395, 21, 56, 1492, 9714, 19854, 9714, 1492, 56, 126, 4991, 51229, 186987, 186987, 51229, 4991, 126, 252, 14848, 251892, 1548002, 3058990, 1548002, 251892, 14848, 252, 462, 39832, 1144205
Offset: 1

Views

Author

R. H. Hardin, Nov 18 2016

Keywords

Comments

Table starts
...0.....0........0..........1............6..............21................56
...0.....3.......20.........94..........395............1492..............4991
...0....20......236.......1678.........9714...........51229............251892
...1....94.....1678......19854.......186987.........1548002..........11947350
...6...395.....9714.....186987......3058990........43798840.........570738085
..21..1492....51229....1548002.....43798840......1133034160.......26606146271
..56..4991...251892...11947350....570738085.....26606146271.....1159826452573
.126.14848..1144205...87562135...7010453565....577253086055....46588303100299
.252.39832..4762445..605431820..82490704797..11856994168275..1741053359883624
.462.97835.18164685.3905165468.927749763030.234252250004719.61687083048618477

Examples

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

Crossrefs

Column 1 is A000389(n+1).

Formula

Empirical for column k:
k=1: a(n) = (1/120)*n^5 - (1/24)*n^4 + (1/24)*n^3 + (1/24)*n^2 - (1/20)*n
k=2: [polynomial of degree 11]
k=3: [polynomial of degree 23]
k=4: [polynomial of degree 47]
k=5: [polynomial of degree 95]

A278778 T(n,k)=Number of nXk 0..1 arrays with rows in nondecreasing lexicographic order and columns in nonincreasing lexicographic order, but with exactly two mistakes.

Original entry on oeis.org

0, 0, 0, 0, 2, 0, 1, 20, 20, 1, 6, 117, 266, 117, 6, 21, 503, 1972, 1972, 503, 21, 56, 1750, 10784, 19750, 10784, 1750, 56, 126, 5209, 48501, 150085, 150085, 48501, 5209, 126, 252, 13751, 189595, 955347, 1673658, 955347, 189595, 13751, 252, 462, 33000
Offset: 1

Views

Author

R. H. Hardin, Nov 28 2016

Keywords

Comments

Table starts
...0.....0.......0.........1...........6............21..............56
...0.....2......20.......117.........503..........1750............5209
...0....20.....266......1972.......10784.........48501..........189595
...1...117....1972.....19750......150085........955347.........5355983
...6...503...10784....150085.....1673658......16205001.......141166787
..21..1750...48501....955347....16205001.....251740932......3634987413
..56..5209..189595...5355983...141166787....3634987413.....90752836672
.126.13751..665212..27218249..1126917480...48847405083...2155380363189
.252.33000.2138149.127644118..8340736743..611199661843..48042054699217
.462.73282.6384894.559023840.57745890265.7140933364136.999491681597761

Examples

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

Crossrefs

Column 1 is A000389(n+1).

Formula

Empirical for column k:
k=1: a(n) = (1/120)*n^5 - (1/24)*n^4 + (1/24)*n^3 + (1/24)*n^2 - (1/20)*n
k=2: [polynomial of degree 10]
k=3: [polynomial of degree 19]
k=4: [polynomial of degree 36]
k=5: [polynomial of degree 69]
k=6: [polynomial of degree 134]

A337895 Number of oriented colorings of the tetrahedral facets (or vertices) of a regular 4-dimensional simplex using n or fewer colors.

Original entry on oeis.org

1, 6, 21, 56, 127, 258, 483, 848, 1413, 2254, 3465, 5160, 7475, 10570, 14631, 19872, 26537, 34902, 45277, 58008, 73479, 92114, 114379, 140784, 171885, 208286, 250641, 299656, 356091, 420762, 494543, 578368, 673233, 780198, 900389, 1035000, 1185295, 1352610
Offset: 1

Views

Author

Robert A. Russell, Sep 28 2020

Keywords

Comments

Each chiral pair is counted as two when enumerating oriented arrangements. Also called a 5-cell or pentachoron. The Schläfli symbol is {3,3,3}, and it has 5 tetrahedral facets (vertices).
There are 60 elements in the rotation group of the 4-dimensional simplex. Each is an even permutation of the vertices and can be associated with a partition of 5 based on the conjugacy class of the permutation. The first formula is obtained by averaging their cycle indices after replacing x_i^j with n^j according to the Pólya enumeration theorem.
Partition Count Even Cycle Indices
5 24 x_5^1
311 20 x_1^2x_3^1
221 15 x_1^1x_2^2
11111 1 x_1^5

Examples

			For a(2)=6, the colors are AAAAA, AAAAB, AAABB, AABBB, ABBBB, and BBBBB.
		

Crossrefs

Cf. A000389(n+4) (unoriented), A000389 (chiral), A132366(n-1) (achiral), A331350 (edges, faces), A337952 (8-cell vertices, 16-cell facets), A337956 (16-cell vertices, 8-cell facets), A338948 (24-cell), A338964 (120-cell, 600-cell).
Row 4 of A324999 (oriented colorings of facets or vertices of an n-simplex).

Programs

  • Mathematica
    Table[n (24 + 35 n^2 + n^4)/60, {n, 40}]
  • PARI
    my(x='x+O('x^39)); Vec(x*(x^4+1)/(x-1)^6) \\ Elmo R. Oliveira, Aug 31 2025

Formula

a(n) = n*(24 + 35*n^2 + n^4)/60.
a(n) = binomial(4+n,5) + binomial(n,5).
a(n) = 1*C(n,1) + 4*C(n,2) + 6*C(n,3) + 4*C(n,4) + 2*C(n,5), where the coefficient of C(n,k) is the number of oriented colorings using exactly k colors.
a(n) = A000389(n+4) + A000389(n) = 2*A000389(n+4) - A132366(n-1) = 2*A000389(n) + A132366(n-1).
From Elmo R. Oliveira, Aug 31 2025: (Start)
G.f.: x*(1 + x^4)/(1 - x)^6.
E.g.f.: x*(60 + 120*x + 60*x^2 + 10*x^3 + x^4)*exp(x)/60.
a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 15*a(n-4) + 6*a(n-5) - a(n-6) for n > 6. (End)

Extensions

More terms from Elmo R. Oliveira, Aug 31 2025

A337954 Number of chiral pairs of colorings of the 16 tetrahedral facets of a hyperoctahedron or of the 16 vertices of a tesseract.

Original entry on oeis.org

0, 94, 97974, 10700090, 390081800, 7280687610, 86121007714, 730895668104, 4816861200630, 26010740238450, 119563513291420, 481192778757834, 1732132086737234, 5669991002636870, 17101193825828700, 48029634770843680
Offset: 1

Views

Author

Robert A. Russell, Oct 03 2020

Keywords

Comments

Each member of a chiral pair is a reflection, but not a rotation, of the other. The Schläfli symbols for the tesseract and the hyperoctahedron are {4,3,3} and {3,3,4} respectively. Both figures are regular 4-D polyhedra and they are mutually dual.

Crossrefs

Cf. A337952 (oriented), A128767 (unoriented), A337955 (achiral).
Other elements: A331360 (tesseract edges, hyperoctahedron faces), A331356 (tesseract faces, hyperoctahedron edges), A234249(n+1) (tesseract facets, hyperoctahedron vertices).
Other polychora: A000389 (4-simplex facets/vertices), A338950 (24-cell), A338966 (120-cell, 600-cell).
Row 4 of A325014 (orthoplex facets, orthotope vertices).

Programs

  • Mathematica
    Table[(n^16-12n^12+12n^10+43n^8-48n^6-44n^4+48n^2)/384,{n, 30}]

Formula

a(n) = (n-1) * n^2 * (n+1) * (n^12 + n^10 - 11*n^8 + n^6 + 44 n^4 - 4 n^2 - 48) / 384.
a(n) = 94*C(n,2) + 97692*C(n,3) + 10308758*C(n,4) + 337560150*C(n,5) + 5098740090*C(n,6) + 42976836210*C(n,7) + 224685801060*C(n,8) + 775389028050*C(n,9) + 1830791421900*C(n,10) + 3007909258200*C(n,11) + 3439214024400*C(n,12) + 2685727044000*C(n,13) + 1366701336000*C(n,14) + 408648240000*C(n,15) + 54486432000*C(n,16), where the coefficient of C(n,k) is the number of chiral pairs of colorings using exactly k colors.
a(n) = A337952(n) - A128767(n) = (A337952(n) - A337955(n)) / 2 = A128767(n) - A337955(n).

A337957 Number of unoriented colorings of the 8 cubic facets of a tesseract or of the 8 vertices of a hyperoctahedron.

Original entry on oeis.org

1, 15, 126, 715, 3060, 10626, 31465, 82251, 194580, 424270, 864501, 1663740, 3049501, 5359095, 9078630, 14891626, 23738715, 36890001, 56031760, 83369265, 121747626, 174792640, 247073751, 344291325, 473490550, 643304376
Offset: 1

Views

Author

Robert A. Russell, Oct 03 2020

Keywords

Comments

Each chiral pair is counted as one when enumerating unoriented arrangements. The Schläfli symbols for the tesseract and the hyperoctahedron are {4,3,3} and {3,3,4} respectively Both figures are regular 4-D polyhedra and they are mutually dual.

Crossrefs

Cf. A337956 (oriented), A234249(n+1) (chiral), A337958 (achiral).
Other elements: A331355 (hyperoctahedron edges, tesseract faces), A331359 (hyperoctahedron faces, tesseract edges), A128767 (hyperoctahedron facets, tesseract vertices).
Other polychora: A000389(n+4) (5-cell), A338949 (24-cell), A338965 (120-cell, 600-cell).
Row 4 of A325005 (orthotope facets, orthoplex vertices).

Programs

  • Mathematica
    Table[Binomial[Binomial[n+1,2]+3,4],{n,30}]

Formula

a(n) = binomial(binomial(n+1,2)+3,4).
a(n) = n * (n+1) * (n^2 + n + 2) * (n^2 + n + 4) * (n^2 + n + 6) / 384.
a(n) = 1*C(n,1) + 13*C(n,2) + 84*C(n,3) + 297*C(n,4) + 600*C(n,5) + 690*C(n,6) + 420*C(n,7) + 105*C(n,8), where the coefficient of C(n,k) is the number of unoriented colorings using exactly k colors.
a(n) = A337956(n) - A234249(n+1) = (A337956(n) + A337958(n)) / 2 = A234249(n+1) + A337958(n).
From Stefano Spezia, Oct 04 2020: (Start)
G.f.: x*(1 + 6*x + 27*x^2 + 37*x^3 + 27*x^4 + 6*x^5 + x^6)/(1 - x)^9.
a(n) = 9*a(n-1)-36*a(n-2)+84*a(n-3)-126*a(n-4)+126*a(n-5)-84*a(n-6)+36*a(n-7)-9*a(n-8)+a(n-8) for n > 8.
(End)
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