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.

A300358 Array read by antidiagonals: T(m,n) = total domination number of the grid graph P_m X P_n.

Original entry on oeis.org

1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 4, 3, 4, 3, 4, 4, 4, 4, 4, 4, 4, 4, 5, 6, 5, 4, 4, 4, 6, 6, 8, 8, 6, 6, 4, 5, 6, 7, 8, 9, 8, 7, 6, 5, 6, 6, 8, 10, 10, 10, 10, 8, 6, 6, 6, 8, 9, 12, 12, 12, 12, 12, 9, 8, 6, 6, 8, 10, 12, 14, 14, 14, 14, 12, 10, 8, 6, 7, 8, 11, 14, 15, 16, 15, 16, 15, 14, 11, 8, 7
Offset: 1

Views

Author

Andrew Howroyd, Apr 20 2018

Keywords

Examples

			Table begins:
=======================================================
m\n| 1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16
---+---------------------------------------------------
1  | 1  2  2  2  3  4  4  4  5  6  6  6  7  8  8  8 ...
2  | 2  2  2  4  4  4  6  6  6  8  8  8 10 10 10 12 ...
3  | 2  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 ...
4  | 2  4  4  6  8  8 10 12 12 14 14 16 18 18 20 20 ...
5  | 3  4  5  8  9 10 12 14 15 16 18 20 21 22 24 26 ...
6  | 4  4  6  8 10 12 14 16 18 20 20 24 24 26 28 30 ...
7  | 4  6  7 10 12 14 15 18 20 22 24 26 27 30 32 34 ...
8  | 4  6  8 12 14 16 18 20 22 24 28 30 32 34 36 38 ...
9  | 5  6  9 12 15 18 20 22 25 28 30 32 35 38 40 42 ...
...
		

Crossrefs

Rows 1..2 are A004524(n+2), A302402.
Main diagonal is A302488.

A303054 Number of minimum total dominating sets in the n-ladder graph.

Original entry on oeis.org

1, 4, 1, 16, 9, 1, 64, 16, 1, 169, 25, 1, 361, 36, 1, 676, 49, 1, 1156, 64, 1, 1849, 81, 1, 2809, 100, 1, 4096, 121, 1, 5776, 144, 1, 7921, 169, 1, 10609, 196, 1, 13924, 225, 1, 17956, 256, 1, 22801, 289, 1, 28561, 324, 1, 35344, 361, 1, 43264, 400, 1, 52441
Offset: 1

Views

Author

Eric W. Weisstein, Apr 17 2018

Keywords

Comments

Each vertex can dominate up to three others. A ladder with a length that is an exact multiple of three can be dominated in only one way with 2n/3 vertices. - Andrew Howroyd, Apr 21 2018

Examples

			From _Andrew Howroyd_, Apr 21 2018: (Start)
a(9) = 1 because there is only one arrangement of 6 vertices that is totally dominating and no set with fewer vertices can be totally dominating:
  .__o__.__.__o__.__.__o__.
     |        |        |
  .__o__.__.__o__.__.__o__.
(End)
		

Crossrefs

Row 2 of A303293.

Programs

  • Mathematica
    Table[Piecewise[{{1, Mod[n, 3] == 0}, {((n^2 + 13 n + 4)/18)^2, Mod[n, 3] == 1}, {((n + 4)/3)^2, Mod[n, 3] == 2}}], {n, 58}] (* Eric W. Weisstein, Apr 23 2018 and Michael De Vlieger, Apr 21 2018 *)
    Table[(916 + 392 n + 213 n^2 + 26 n^3 + n^4 - (-56 + 392 n + 213 n^2 + 26 n^3 + n^4) Cos[2 n Pi/3] + Sqrt[3] (-20 + 7 n + n^2) (28 + 19 n + n^2) Sin[2 n Pi/3])/972, {n, 20}] (* Eric W. Weisstein, Apr 23 2018 *)
    LinearRecurrence[{0, 0, 5, 0, 0, -10, 0, 0, 10, 0, 0, -5, 0, 0, 1}, {1, 4, 1, 16, 9, 1, 64, 16, 1, 169, 25, 1, 361, 36, 1}, 20] (* Eric W. Weisstein, Apr 23 2018 *)
    CoefficientList[Series[(-1 - 4 x - x^2 - 11 x^3 + 11 x^4 + 4 x^5 + 6 x^6 - 11 x^7 - 6 x^8 + x^9 + 5 x^10 + 4 x^11 - x^12 - x^13 - x^14)/(-1 + x^3)^5, {x, 0, 20}], x] (* Eric W. Weisstein, Apr 23 2018 *)
  • PARI
    a(n)={if(n%3==0, 1, if(n%3==1, (n^2 + 13*n + 4)/18, (n + 4)/3))^2} \\ Andrew Howroyd, Apr 21 2018
    
  • PARI
    Vec(x*(1 + 4*x + x^2 + 11*x^3 - 11*x^4 - 4*x^5 - 6*x^6 + 11*x^7 + 6*x^8 - x^9 - 5*x^10 - 4*x^11 + x^12 + x^13 + x^14) / ((1 - x)^5*(1 + x + x^2)^5) + O(x^60)) \\ Colin Barker, Apr 23 2018

Formula

a(n) = 1 for n mod 3 = 0
= ((n^2 + 13*n + 4)/18)^2 for n mod 3 = 1
= ((n + 4)/3)^2 for n mod 3 = 2.
G.f.: x*(-1 - 4*x - x^2 - 11*x^3 + 11*x^4 + 4*x^5 + 6*x^6 - 11*x^7 - 6*x^8 + x^9 + 5*x^10 + 4*x^11 - x^12 - x^13 - x^14)/(-1 + x^3)^5.
a(n) = 5*a(n-3) - 10*a(n-6) + 10*a(n-9) - 5*a(n-12) + a(n-15) for n>15. - Colin Barker, Apr 23 2018

Extensions

Terms a(14) and beyond from Andrew Howroyd, Apr 21 2018

A303072 Number of minimal total dominating sets in the n-ladder graph.

Original entry on oeis.org

1, 4, 4, 16, 16, 49, 81, 169, 324, 625, 1296, 2401, 4900, 9409, 18769, 36481, 71824, 141376, 276676, 544644, 1067089, 2099601, 4116841, 8088336, 15880225, 31181056, 61230625, 120209296, 236083225, 463497841, 910168561, 1787091076, 3509140644, 6890328064, 13529411856
Offset: 1

Views

Author

Eric W. Weisstein, Apr 18 2018

Keywords

Crossrefs

Row 2 of A303118.

Programs

  • Mathematica
    Table[(RootSum[1 - #^2 - #^3 - #^4 + #^6 &, (9 - 18 #^2 + 23 #^3 - 3 #^4 + 32 #^5) #^n &]/229)^2, {n, 40}]
    LinearRecurrence[{-1, 1, 3, 7, 8, 2, 6, 6, 0, 0, -6, -6, -2, -8, -7, -3, -1, 1, 1}, {1, 4, 4, 16, 16, 49, 81, 169,324, 625, 1296, 2401, 4900, 9409, 18769, 36481, 71824, 141376, 276676}, 40]
    CoefficientList[Series[(-1 - 5 x - 7 x^2 - 13 x^3 - 9 x^4 - x^5 - 4 x^6 + 5 x^7 + 13 x^8 + 14 x^9 + 21 x^10 + 15 x^11 + 12 x^12 + 15 x^13 + 9 x^14 + 3 x^15 - 2 x^17 - x^18)/(-1 - x + x^2 + 3 x^3 + 7 x^4 + 8 x^5 + 2 x^6 + 6 x^7 + 6 x^8 - 6 x^11 - 6 x^12 - 2 x^13 - 8 x^14 - 7 x^15 - 3 x^16 - x^17 + x^18 + x^19), {x, 0, 40}], x]

Formula

a(n) = A253412(n)^2.
G.f.: x*(-1 - 5*x - 7*x^2 - 13*x^3 - 9*x^4 - x^5 - 4*x^6 + 5*x^7 + 13*x^8 + 14*x^9 + 21*x^10 + 15*x^11 + 12*x^12 + 15*x^13 + 9*x^14 + 3*x^15 - 2*x^17 - x^18)/(-1 - x + x^2 + 3*x^3 + 7*x^4 + 8*x^5 + 2*x^6 + 6*x^7 + 6*x^8 - 6*x^11 - 6*x^12 - 2*x^13 - 8*x^14 - 7*x^15 - 3*x^16 - x^17 + x^18 + x^19).

A063279 Dimension of the space of weight n cuspidal newforms for Gamma_1( 6 ).

Original entry on oeis.org

-1, 0, 0, 1, 2, 1, 2, 1, 2, 1, 4, 3, 4, 1, 4, 3, 6, 3, 6, 3, 6, 3, 8, 5, 8, 3, 8, 5, 10, 5, 10, 5, 10, 5, 12, 7, 12, 5, 12, 7, 14, 7, 14, 7, 14, 7, 16, 9, 16, 7, 16, 9, 18, 9, 18, 9, 18, 9, 20, 11, 20, 9, 20, 11, 22, 11, 22, 11, 22, 11, 24, 13, 24, 11, 24, 13, 26, 13
Offset: 2

Views

Author

N. J. A. Sloane, Jul 14 2001

Keywords

Crossrefs

Cf. A302402 (bisection), A063195 (bisection)

Formula

g.f.: x^2*(x^9-2*x^8+2*x^6-2*x^5+3*x^4+x-1) / ((x-1)^2*(x+1)^2*(x^2-x+1)*(x^2+1)). - Colin Barker, Feb 24 2015
Showing 1-4 of 4 results.