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 1-3 of 3 results.

A259222 T(n,k) is the number of (n+1) X (k+1) 0..1 arrays with each 2 X 2 subblock having clockwise pattern 0000 0011 or 0101.

Original entry on oeis.org

7, 13, 13, 24, 23, 24, 45, 40, 40, 45, 85, 71, 66, 71, 85, 162, 127, 112, 112, 127, 162, 311, 230, 192, 183, 192, 230, 311, 601, 421, 334, 303, 303, 334, 421, 601, 1168, 779, 588, 510, 487, 510, 588, 779, 1168, 2281, 1456, 1048, 869, 798, 798, 869, 1048, 1456, 2281
Offset: 1

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Author

R. H. Hardin, Jun 21 2015

Keywords

Comments

Table starts
7 13 24 45 85 162 311 601 1168 2281 4473 8802 17371
13 23 40 71 127 230 421 779 1456 2747 5227 10022 19345
24 40 66 112 192 334 588 1048 1890 3448 6360 11854 22308
45 71 112 183 303 510 869 1499 2616 4619 8251 14910 27249
85 127 192 303 487 798 1325 2227 3784 6499 11283 19806 35161
162 230 334 510 798 1278 2078 3422 5694 9566 16222 27774 48030
311 421 588 869 1325 2078 3319 5377 8804 14545 24225 40670 68843
601 779 1048 1499 2227 3422 5377 8591 13888 22655 37231 61598 102589
1168 1456 1890 2616 3784 5694 8804 13888 22210 35872 58368 95550 157276
2281 2747 3448 4619 6499 9566 14545 22655 35872 57455 92767 150686 245965
Each row (and each column, by symmetry) has a rational generating function (and therefore a linear recurrence with constant coefficients) because the growth from an array to the next larger one is described by the transfer matrix method. - R. J. Mathar, Oct 09 2020

Examples

			Some solutions for n=4, k=4:
  0 0 1 0 1      1 1 1 0 1      0 0 0 0 1      0 0 0 1 0
  0 0 1 0 1      0 0 0 1 0      0 0 0 0 1      0 0 0 1 0
  1 1 0 1 0      0 0 0 1 0      1 1 1 1 0      0 0 0 1 0
  0 0 1 0 1      0 0 0 1 0      0 0 0 0 1      1 1 1 0 1
  1 1 0 1 0      0 0 0 1 0      0 0 0 0 1      0 0 0 1 0
		

Crossrefs

Formula

Empirical for diagonal and column k (k=3..7 recurrences work also for k=1,2):
diagonal: a(n) = 6*a(n-1) - 10*a(n-2) - 2*a(n-3) + 16*a(n-4) - 6*a(n-5) - 5*a(n-6) + 2*a(n-7).
k=1: a(n) = 3*a(n-1) - a(n-2) - 2*a(n-3)
k=2: a(n) = 3*a(n-1) - a(n-2) - 2*a(n-3)
k=3: a(n) = 4*a(n-1) - 4*a(n-2) - a(n-3) + 2*a(n-4)
k=4: a(n) = 4*a(n-1) - 4*a(n-2) - a(n-3) + 2*a(n-4)
k=5: a(n) = 4*a(n-1) - 4*a(n-2) - a(n-3) + 2*a(n-4)
k=6: a(n) = 4*a(n-1) - 4*a(n-2) - a(n-3) + 2*a(n-4)
k=7: a(n) = 4*a(n-1) - 4*a(n-2) - a(n-3) + 2*a(n-4)
Empirical: T(n,k) = 2^(k+1) + 2^(n+1) + F(n+3)*F(k+3) - 2*F(n+3) - 2*F(k+3) + 2 = 2^(n+1) + A001911(k)*F(n+3) + A234933(k+1) = A234933(n+1) + A234933(k+1) + A143211(n+3,k+3) - 2, F=A000045. - Ehren Metcalfe, Dec 27 2018

A098356 Multiplication table of the Fibonacci numbers read by antidiagonals.

Original entry on oeis.org

0, 0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 2, 1, 2, 0, 0, 3, 2, 2, 3, 0, 0, 5, 3, 4, 3, 5, 0, 0, 8, 5, 6, 6, 5, 8, 0, 0, 13, 8, 10, 9, 10, 8, 13, 0, 0, 21, 13, 16, 15, 15, 16, 13, 21, 0, 0, 34, 21, 26, 24, 25, 24, 26, 21, 34, 0, 0, 55, 34, 42, 39, 40, 40, 39, 42, 34, 55, 0, 0, 89, 55, 68, 63, 65, 64, 65
Offset: 0

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Author

Douglas Stones (dssto1(AT)student.monash.edu.au), Sep 04 2004

Keywords

Comments

Same as triangle T(n,k) = F(n)-F(k)*F(n-k+1), read by rows, F(i) = A000045(i). - Dale Gerdemann, Apr 24 2016

Examples

			Table begins:
   0   0   0   0   0   0   0   0   0 ...
   0   1   1   2   3   5   8  13  21...
   0   1   1   2   3   5   8  13  21...
   0   2   2   4   6  10  16  26  42...
   0   3   3   6   9  15  24  39  63...
   0   5   5  10  15  25  40  65 105...
   0   8   8  16  24  40  64 104 168...
   0  13  13  26  39  65 104 169 273...
   0  21  21  42  63 105 168 273 441...
		

Crossrefs

Cf. A003991, A058071, A001629 (antidiagonal sums).

Programs

  • Mathematica
    Table[Fibonacci[n] - Fibonacci[k]*Fibonacci[n - k + 1], {n, 13}, {k, n}] // Flatten (* Michael De Vlieger, Dec 11 2020 *)

Formula

T(n,k) = T(k,n) = A000045(n)*A000045(k) = A143211(n,k). - R. J. Mathar, Dec 11 2020

A143212 a(n) = Fibonacci(n) * (Fibonacci(n+2) - 1).

Original entry on oeis.org

1, 2, 8, 21, 60, 160, 429, 1134, 2992, 7865, 20648, 54144, 141897, 371722, 973560, 2549421, 6675460, 17478176, 45761045, 119808150, 313668576, 821205937, 2149962768, 5628704256, 14736185425, 38579909330, 101003635304
Offset: 1

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Author

Gary W. Adamson, Jul 30 2008

Keywords

Comments

Lim_{n -> oo} a(n)/a(n-1) tends to phi^2.
a(n) = Product of sum of first n Fibonacci numbers and Fibonacci number(n). - Vladimir Joseph Stephan Orlovsky, Oct 13 2009

Examples

			a(5) = 60 = F(5) * (F(7)-1) = 5*12.
a(5) = 60 = sum of row 5 terms of triangle A143211: (5 + 5 + 10 + 15 + 25).
		

Crossrefs

Programs

  • Magma
    [Fibonacci(n)*(Fibonacci(n+2)-1): n in [1..40]]; // G. C. Greubel, Jul 21 2024
    
  • Mathematica
    LinearRecurrence[{3,1,-5,-1,1}, {1,2,8,21,60}, 40] (* Vladimir Joseph Stephan Orlovsky, Oct 13 2009 *)
    Table[Fibonacci[n](Fibonacci[n+2]-1),{n,30}] (* Harvey P. Dale, Dec 14 2012 *)
  • SageMath
    [fibonacci(n)*(fibonacci(n+2)-1) for n in range(1,41)] # G. C. Greubel, Jul 21 2024

Formula

a(n) = A000045(n) * A000071(n+2).
a(n) = Sum_{k=1..n} A143211(n, k) (row sums of A143211).
From R. J. Mathar, Sep 06 2008: (Start)
G.f.: (1-x+x^2)/((1+x)*(1-3*x+x^2)*(1-x-x^2)).
a(n) = (-5*A000045(n+1) + 3*(-1)^n + 7*A001906(n+1) -3*A001906(n))/5. (End)
a(n) = Fibonacci(n)*Sum_{k=0..n} Fibonacci(k). - Paul Barry, Jan 05 2009
Showing 1-3 of 3 results.