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.

A100314 Number of 2 X n 0-1 matrices avoiding simultaneously the right angled numbered polyomino patterns (ranpp) (00;1), (01;0), (10;0) and (01;1).

Original entry on oeis.org

1, 4, 8, 14, 24, 42, 76, 142, 272, 530, 1044, 2070, 4120, 8218, 16412, 32798, 65568, 131106, 262180, 524326, 1048616, 2097194, 4194348, 8388654, 16777264, 33554482, 67108916, 134217782, 268435512, 536870970, 1073741884, 2147483710, 4294967360, 8589934658
Offset: 0

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Author

Sergey Kitaev, Nov 13 2004

Keywords

Comments

An occurrence of a ranpp (xy;z) in a matrix A=(a(i,j)) is a triple (a(i1,j1), a(i1,j2), a(i2,j1)) where i1 < i2, j1 < j2 and these elements are in the same relative order as those in the triple (x,y,z). In general, the number of m X n 0-1 matrices in question is given by 2^m + 2^n + 2*(n*m-n-m).

References

  • Arthur H. Stroud, Approximate calculation of multiple integrals, Prentice-Hall, 1971.

Crossrefs

Cf. this sequence (m=2), A100315 (m=3), A100316 (m=4).
Row sums of A131830.

Programs

Formula

a(n) = 2^n + 2*n.
From Gary W. Adamson, Jul 20 2007: (Start)
Binomial transform of (1, 3, 1, 1, 1, ...).
For n > 0, a(n) = 2*A005126(n-1). (End)
From R. J. Mathar, Jun 13 2008: (Start)
G.f.: 1 + 2*x*(2 -4*x +x^2)/((1-x)^2*(1-2*x)).
a(n+1)-a(n) = A052548(n). (End)
From Colin Barker, Oct 16 2013: (Start)
a(n) = 4*a(n-1) - 5*a(n-2) + 2*a(n-3).
G.f.: (1 - 3*x^2)/((1-x)^2*(1-2*x)). (End)
E.g.f.: exp(2*x) + 2*x*exp(x). - Franck Maminirina Ramaharo, Dec 19 2018
a(n) = A000079(n) + A005843(n). - Muniru A Asiru, Dec 21 2018

Extensions

a(0)=1 prepended by Alois P. Heinz, Dec 21 2018

A135224 Triangle A103451 * A007318 * A000012, read by rows. T(n, k) for 0 <= k <= n.

Original entry on oeis.org

1, 3, 1, 5, 3, 1, 9, 7, 4, 1, 17, 15, 11, 5, 1, 33, 31, 26, 16, 6, 1, 65, 63, 57, 42, 22, 7, 1, 129, 127, 120, 99, 64, 29, 8, 1, 257, 255, 247, 219, 163, 93, 37, 9, 1, 513, 511, 502, 466, 382, 256, 130, 46, 10, 1
Offset: 0

Views

Author

Gary W. Adamson, Nov 23 2007

Keywords

Comments

Row sums = A132750: (1, 4, 9, 21, 49, 113, ...).
Left border = A083318: (1, 3, 5, 9, 17, 33, ...).

Examples

			First few rows of the triangle:
   1;
   3,  1;
   5,  3,  1;
   9,  7,  4,  1;
  17, 15, 11,  5,  1;
  33, 31, 26, 16,  6,  1;
  65, 63, 57, 42, 22,  7,  1;
...
		

Crossrefs

Programs

  • Magma
    function T(n,k)
      if k eq 0 and n eq 0 then return 1;
      elif k eq 0 then return 2^n +1;
      else return (&+[Binomial(n, k+j): j in [0..n]]);
      end if; return T; end function;
    [T(n,k): k in [0..n], n in [0..10]]; // G. C. Greubel, Nov 20 2019
    
  • Maple
    T:= proc(n, k) option remember;
          if k=0 and n=0 then 1
        elif k=0 then 2^n +1
        else add(binomial(n, k+j), j=0..n)
          fi; end:
    seq(seq(T(n, k), k=0..n), n=0..10); # G. C. Greubel, Nov 20 2019
  • Mathematica
    T[n_, k_]:= T[n, k] = If[k==n==0, 1, If[k==0, 2^n +1, Sum[Binomial[n, k + j], {j, 0, n}]]]; Table[T[n, k], {n, 0, 10}, {k, 0, n}]//Flatten (* G. C. Greubel, Nov 20 2019 *)
  • PARI
    T(n,k) = if(k==0 && n==0, 1, if(k==0, 2^n +1, sum(j=0, n, binomial(n, k+j)) )); \\ G. C. Greubel, Nov 20 2019
    
  • Sage
    def T(n, k):
        if (k==0 and n==0): return 1
        elif (k==0): return 2^n + 1
        else: return sum(binomial(n, k+j) for j in (0..n))
    [[T(n, k) for k in (0..n)] for n in (0..10)] # G. C. Greubel, Nov 20 2019

Formula

T(n, k) = A103451(n,k) * A007318(n,k) * A000012(n,k) as infinite lower triangular matrices.
T(n, k) = Sum_{j=0..n} binomial(n, k+j), with T(0,0) = 1 and T(n,0) = 2^n + 1. - G. C. Greubel, Nov 20 2019
T(n, k) = binomial(n, k)*hypergeom([1, k-n], [k+1], -1) - binomial(n, k+n+1)* hypergeom([1, k+1], [k+n+2], -1) + 0^k - 0^n. - Peter Luschny, Nov 20 2019

A321123 a(n) = 2^n + 2*n^2 + 2*n + 1.

Original entry on oeis.org

2, 7, 17, 33, 57, 93, 149, 241, 401, 693, 1245, 2313, 4409, 8557, 16805, 33249, 66081, 131685, 262829, 525049, 1049417, 2098077, 4195317, 8389713, 16778417, 33555733, 67110269, 134219241, 268437081, 536872653, 1073743685, 2147485633, 4294969409, 8589936837
Offset: 0

Views

Author

Keywords

Comments

For n >= 2, a(n) is the number of evaluation points on the n-dimensional cube in Genz and Malik's degree 7 cubature rule.

Crossrefs

Programs

  • Magma
    [2^n + 2*n^2 + 2*n + 1: n in [0..33]]; // Marius A. Burtea, Dec 28 2018
  • Mathematica
    Table[2^n + 2*n^2 + 2*n + 1, {n, 0, 50}]
  • Maxima
    makelist(2^n + 2*n^2 + 2*n + 1, n, 0, 50);
    

Formula

a(n) = A000079(n) + A001844(n).
a(n) = 5*a(n-1) - 9*a(n-2) + 7*a(n-3) - 2*a(n-4), n >= 4.
G.f.: (2 - 3*x - 3*x^3)/((1 - 2*x)*(1 - x)^3).
E.g.f.: exp(2*x) + (1 + 4*x + 2*x^2)*exp(x).

A322593 a(n) = 2^n + 2*n^2 + 1.

Original entry on oeis.org

2, 5, 13, 27, 49, 83, 137, 227, 385, 675, 1225, 2291, 4385, 8531, 16777, 33219, 66049, 131651, 262793, 525011, 1049377, 2098035, 4195273, 8389667, 16778369, 33555683, 67110217, 134219187, 268437025, 536872595, 1073743625, 2147485571, 4294969345, 8589936771
Offset: 0

Views

Author

Keywords

Comments

For n = 3..7, a(n) is the number of evaluating points on the n-dimensional sphere (also n-space with weight function exp(-r^2) or exp(-r)) in a degree 7 cubature rule.

References

  • Arthur H. Stroud, Approximate calculation of multiple integrals, Prentice-Hall, 1971.

Crossrefs

Programs

  • Magma
    [2^n + 2*n^2 + 1: n in [0..33]]; // Marius A. Burtea, Dec 28 2018
  • Mathematica
    Table[2^n + 2*n^2 + 1, {n, 0, 50}]
    LinearRecurrence[{5,-9,7,-2},{2,5,13,27},50] (* Harvey P. Dale, Mar 23 2021 *)
  • Maxima
    makelist(2^n + 2*n^2 + 1, n, 0, 50);
    

Formula

a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4), n >= 4.
a(n) = a(n-1) + A100315(n-1), n >= 2.
G.f.: (2 - 5*x + 6*x^2 - 7*x^3)/((1 - 2*x)*(1 - x)^3)
E.g.f.: exp(2*x) + (1 + 2*x + 2*x^2)*exp(x).
Showing 1-4 of 4 results.