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.

A108036 Triangle read by rows: the triangle in A108035 surrounded by a border of 0's.

Original entry on oeis.org

0, 0, 0, 0, 1, 0, 0, 2, 2, 0, 0, 3, 3, 3, 0, 0, 5, 5, 5, 5, 0, 0, 8, 8, 8, 8, 8, 0, 0, 13, 13, 13, 13, 13, 13, 0, 0, 21, 21, 21, 21, 21, 21, 21, 0, 0, 34, 34, 34, 34, 34, 34, 34, 34, 0, 0, 55, 55, 55, 55, 55, 55, 55, 55, 55, 0, 0, 89, 89, 89, 89, 89, 89, 89, 89, 89, 89, 0, 0, 144, 144, 144, 144
Offset: 0

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Author

N. J. A. Sloane, Jun 01 2005

Keywords

Examples

			0; 0,0; 0,1,0; 0,2,2,0; 0,3,3,3,0; 0,5,5,5,5,0; ...
		

Crossrefs

Programs

  • Python
    from math import isqrt
    from sympy import fibonacci
    def A108036(n): return 0 if 0<=(k:=n+1<<1)-(r:=(m:=isqrt(k))*(m+1))<=2 or n<=1 else int(fibonacci(m-(k<=r))) # Chai Wah Wu, Nov 07 2024

Formula

G.f.: x*y*(1+x+y)/((1-x-x^2)*(1-y-y^2)). [U coordinates]

A023607 a(n) = n * Fibonacci(n+1).

Original entry on oeis.org

0, 1, 4, 9, 20, 40, 78, 147, 272, 495, 890, 1584, 2796, 4901, 8540, 14805, 25552, 43928, 75258, 128535, 218920, 371931, 630454, 1066464, 1800600, 3034825, 5106868, 8580897, 14398412, 24129160, 40388070, 67527579, 112786496, 188195271
Offset: 0

Views

Author

Keywords

Comments

Convolution of Fibonacci numbers and Lucas numbers.
Central terms of the triangle in A119457 for n>0. - Reinhard Zumkeller, May 20 2006
d/dx(1 + x + 2x^2 + 3x^3 + 5x^4 + 8x^5 + ...) = (1 + 4x + 9x^2 + ...). - Gary W. Adamson, Jun 27 2009
For n > 0: sums of rows of the triangle in A108035. - Reinhard Zumkeller, Oct 08 2012

Crossrefs

First differences of A094584.
Second column of triangle A016095.

Programs

  • Haskell
    a023607 n = a023607_list !! n
    a023607_list = zipWith (*) [0..] $ tail a000045_list
    -- Reinhard Zumkeller, Oct 08 2012
    
  • Maple
    A023607 := proc(n)
        n*combinat[fibonacci](n+1) ;
    end proc:
    seq(A023607(n),n=0..10) ; # R. J. Mathar, Jul 15 2017
  • Mathematica
    Times@@@Thread[{Range[0, 50], Fibonacci[Range[51]]}]  (* Harvey P. Dale, Mar 08 2011 *)
    Table[n*Fibonacci[n + 1], {n, 0, 50}]
  • PARI
    a(n)=n*fibonacci(n+1) \\ Charles R Greathouse IV, Sep 24 2015

Formula

O.g.f.: x(2x+1)/(1-x-x^2)^2. - Len Smiley, Dec 11 2001
a(n) = n*Sum_{k=0..n} binomial(k,n-k). - Paul Barry, Sep 25 2004
a(n) = A215082(2n-2) + A215082(2n-1). - Philippe Deléham, Aug 03 2012
a(n) = Sum_{i=1..n} A000045(i)*A000032(n-i+1). - Vladimir Kruchinin, Nov 08 2013

Extensions

Simpler description from Samuel Lachterman (slachterman(AT)fuse.net), Sep 19 2003
Name improved by T. D. Noe, Mar 08 2011

A039913 Triangular "Fibonacci array".

Original entry on oeis.org

0, 1, 1, 1, 2, 1, 2, 3, 3, 2, 3, 5, 4, 5, 3, 5, 8, 7, 7, 8, 5, 8, 13, 11, 12, 11, 13, 8, 13, 21, 18, 19, 19, 18, 21, 13, 21, 34, 29, 31, 30, 31, 29, 34, 21, 34, 55, 47, 50, 49, 49, 50, 47, 55, 34, 55, 89, 76, 81, 79, 80, 79, 81, 76, 89, 55, 89, 144, 123, 131, 128, 129, 129, 128
Offset: 0

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Author

Keywords

Comments

Sum of n-th row = 2*A001629(n+1). - Reinhard Zumkeller, Oct 07 2012

Examples

			0;
1 1;
1 2 1;
2 3 3 2;
3 5 4 5 3;
...
		

Crossrefs

Cf. A108035.

Programs

  • Haskell
    a039913 n k = a039913_tabl !! n !! k
    a039913_row n = a039913_tabl !! n
    a039913_tabl = [[0], [1, 1]] ++ f [0] [1, 1] where
       f us@(u:us') vs@(v:vs') = ws : f vs ws where
         ws = [u + v, u + v + v] ++ zipWith (+) us vs'
    -- Reinhard Zumkeller, Oct 07 2012

Formula

a(0, n)=Fib(n), a(1, n)=Fib(n+2), a(r, n)=a(r-1, n)+a(r-2, n), r >= 2.
G.f.: (x+y)/((1-x-x^2)*(1-y-y^2)). [U coordinates]

Extensions

More terms from Larry Reeves (larryr(AT)acm.org), Sep 28 2000

A108037 Triangle read by rows: n-th row is n-th nonzero Fibonacci number repeated n+1 times.

Original entry on oeis.org

0, 1, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 5, 5, 5, 5, 5, 5, 8, 8, 8, 8, 8, 8, 8, 13, 13, 13, 13, 13, 13, 13, 13, 21, 21, 21, 21, 21, 21, 21, 21, 21, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 55, 55, 55, 55, 55, 55, 55, 55, 55, 55, 55, 89, 89, 89, 89, 89, 89, 89, 89, 89, 89, 89, 89, 144, 144
Offset: 0

Views

Author

N. J. A. Sloane, Jun 01 2005

Keywords

Examples

			0; 1,1; 1,1,1; 2,2,2,2; 3,3,3,3,3; 5,5,5,5,5,5; ...
		

Crossrefs

Cf. A099920 (row sums).

Programs

  • Haskell
    a108037 n k = a108037_tabl !! n !! k
    a108037_row n = a108037_tabl !! n
    a108037_tabl = zipWith replicate [1..] a000045_list
    -- Reinhard Zumkeller, Oct 07 2012
    
  • Mathematica
    Table[Table[Fibonacci[n],{n+1}],{n,0,12}]//Flatten (* Harvey P. Dale, May 07 2017 *)
  • Python
    from math import isqrt
    from sympy import fibonacci
    def A108037(n): return int(fibonacci((m:=isqrt(k:=n+1<<1))-(k<=m*(m+1)))) # Chai Wah Wu, Nov 07 2024

Formula

G.f.: x*(1+y-x*y)/((1-x-x^2)*(1-x*y-x^2*y^2)). [U coordinates]
Showing 1-4 of 4 results.