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.

Previous Showing 11-15 of 15 results.

A286394 Number of inequivalent n X n matrices over GF(8) under action of dihedral group of the square D_4.

Original entry on oeis.org

1, 8, 666, 16912512, 35184646816768, 4722366500530551259136, 40564819207305653446303190876160, 22300745198530623151211847196048401987796992, 784637716923335095479473759060307277562325323313332617216
Offset: 0

Views

Author

María Merino, Imanol Unanue, Yosu Yurramendi, May 08 2017

Keywords

Comments

Burnside's orbit-counting lemma.

Crossrefs

Formula

a(n) = (1/8)*(8^(n^2) + 2*8^(n^2/4) + 3*8^(n^2/2) + 2*8^((n^2 + n)/2)) if n is even;
a(n) = (1/8)*(8^(n^2) + 2*8^((n^2 + 3)/4) + 8^((n^2 + 1)/2) + 4*8^((n^2 +n)/2)) if n is odd.

A343875 Array read by antidiagonals: T(n,k) is the number of n X n nonnegative integer matrices with sum of elements equal to k, up to rotations and reflections.

Original entry on oeis.org

1, 0, 1, 0, 1, 1, 0, 1, 1, 1, 0, 1, 3, 3, 1, 0, 1, 4, 11, 3, 1, 0, 1, 8, 31, 24, 6, 1, 0, 1, 10, 84, 113, 55, 6, 1, 0, 1, 16, 198, 528, 410, 99, 10, 1, 0, 1, 20, 440, 2003, 2710, 1091, 181, 10, 1, 0, 1, 29, 904, 6968, 15233, 10488, 2722, 288, 15, 1, 0, 1, 35, 1766, 21593, 75258, 82704, 34399, 5806, 461, 15, 1
Offset: 0

Views

Author

Andrew Howroyd, May 06 2021

Keywords

Examples

			Array begins:
=====================================================
n\k | 0  1   2    3     4      5       6        7
----+------------------------------------------------
  0 | 1  0   0    0     0      0       0        0 ...
  1 | 1  1   1    1     1      1       1        1 ...
  2 | 1  1   3    4     8     10      16       20 ...
  3 | 1  3  11   31    84    198     440      904 ...
  4 | 1  3  24  113   528   2003    6968    21593 ...
  5 | 1  6  55  410  2710  15233   75258   331063 ...
  6 | 1  6  99 1091 10488  82704  563864  3376134 ...
  7 | 1 10 181 2722 34399 360676 3235551 25387944 ...
  ...
		

Crossrefs

Rows n=0..3 are A000007, A000012, A005232, A054343.
Columns 0..1 are A000012, A008805(n-1).
Cf. A054252 (binary case), A318795, A343097, A343874.

Programs

  • PARI
    U(n,s) = {(s(1)^(n^2) + s(1)^(n%2)*(2*s(4)^(n^2\4) + s(2)^(n^2\2)) + 2*s(1)^n*s(2)^(n*(n-1)/2) + 2*(s(1)^(n%2)*s(2)^(n\2))^n )/8}
    T(n,k)={polcoef(U(n,i->1/(1-x^i) + O(x*x^k)), k)}

A217338 Number of inequivalent ways to color a 4 X 4 checkerboard using at most n colors allowing rotations and reflections.

Original entry on oeis.org

0, 1, 8548, 5398083, 537157696, 19076074375, 352654485156, 4154189102413, 35184646816768, 231628411446741, 1250002537502500, 5743722797690911, 23110548002468928, 83177110918426603, 272244240093265636, 821051189587805625, 2305843285702230016, 6082649491072763593
Offset: 0

Views

Author

Geoffrey Critzer, Oct 01 2012

Keywords

Comments

Cycle index of symmetry group: (s(1)^16 + 2*s(4)^4 + 3*s(2)^8 + 2*s(2)^6*s(1)^4)/8.

Crossrefs

Row n=4 of A343097.

Programs

  • Mathematica
    Table[(n^16+2n^4+3n^8+2n^10)/8, {n,0,20}]
  • PARI
    a(n) = (n^16 + 2*n^4 + 3*n^8 + 2*n^10)/8; \\ Indranil Ghosh, Feb 27 2017
    
  • Python
    def A217338(n): return (n**16 + 2*n**4 + 3*n**8 + 2*n**10)/8 # Indranil Ghosh, Feb 27 2017

Formula

a(n) = (n^16 + 2*n^4 + 3*n^8 + 2*n^10)/8.
G.f.: -x*(x +1)*(x^14 +8530*x^13 +5244373*x^12 +441307760*x^11 +10231414811*x^10 +87532894238*x^9 +313403397135*x^8 +484445834304*x^7 +313403397135*x^6 +87532894238*x^5 +10231414811*x^4 +441307760*x^3 +5244373*x^2 +8530*x +1)/(x -1)^17. [Colin Barker, Oct 04 2012]

A286396 Number of inequivalent n X n matrices over GF(9) under action of dihedral group of the square D_4.

Original entry on oeis.org

1, 9, 1035, 48700845, 231628411446741, 89737248564744874067889, 2816049943117424212512789695666175, 7158021121277935153545945911617993395398302485, 1473773072217322896440109113309952350877179744639518847951721
Offset: 0

Views

Author

María Merino, Imanol Unanue, Yosu Yurramendi, May 08 2017

Keywords

Comments

Burnside's orbit-counting lemma.

Crossrefs

Programs

  • Mathematica
    Table[1/8*(9^(n^2) + 2*9^((n^2 + 3 #)/4) + (3 - 2 #)*9^((n^2 + #)/2) + (2 + 2 #)*9^((n^2 + n)/2)) &@ Boole@ OddQ@ n, {n, 0, 7}] (* Michael De Vlieger, May 12 2017 *)

Formula

a(n) = (1/8)*(9^(n^2) + 2*9^(n^2/4) + 3*9^(n^2/2) + 2*9^((n^2 + n)/2)) if n is even;
a(n) = (1/8)*(9^(n^2) + 2*9^((n^2 + 3)/4) + 9^((n^2 + 1)/2) + 4*9^((n^2 + n)/2)) if n is odd.

A286397 Number of inequivalent n X n matrices over an alphabet of size 10 under action of dihedral group of the square D_4.

Original entry on oeis.org

1, 10, 1540, 125512750, 1250002537502500, 1250000000501250002500000, 125000000000000250375000000250000000, 1250000000000000000005001250000000002500000000000
Offset: 0

Views

Author

María Merino, Imanol Unanue, Yosu Yurramendi, May 08 2017

Keywords

Comments

Burnside's orbit-counting lemma.

Crossrefs

Programs

  • Mathematica
    Table[1/8*(10^(n^2) + 2*10^((n^2 + 3 #)/4) + (3 - 2 #)*10^((n^2 + #)/2) + (2 + 2 #)*10^((n^2 + n)/2)) &@ Boole@ OddQ@ n, {n, 7}] (* Michael De Vlieger, May 12 2017 *)

Formula

a(n) = (1/8)*(10^(n^2) + 2*10^(n^2/4) + 3*10^(n^2/2) + 2*10^((n^2 + n)/2)) if n is even;
a(n) = (1/8)*(10^(n^2) + 2*10^((n^2 + 3)/4) + 10^((n^2 + 1)/2) + 4*10^((n^2 + n)/2)) if n is odd.
Previous Showing 11-15 of 15 results.