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.

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A107430 Triangle read by rows: row n is row n of Pascal's triangle (A007318) sorted into increasing order.

Original entry on oeis.org

1, 1, 1, 1, 1, 2, 1, 1, 3, 3, 1, 1, 4, 4, 6, 1, 1, 5, 5, 10, 10, 1, 1, 6, 6, 15, 15, 20, 1, 1, 7, 7, 21, 21, 35, 35, 1, 1, 8, 8, 28, 28, 56, 56, 70, 1, 1, 9, 9, 36, 36, 84, 84, 126, 126, 1, 1, 10, 10, 45, 45, 120, 120, 210, 210, 252, 1, 1, 11, 11, 55, 55, 165, 165, 330, 330, 462, 462, 1
Offset: 0

Views

Author

Philippe Deléham, May 21 2005

Keywords

Comments

By rows, equals partial sums of A053121 reversed rows. Example: Row 4 of A053121 = (2, 0, 3, 0, 1) -> (1, 0, 3, 0, 2) -> (1, 1, 4, 4, 6). - Gary W. Adamson, Dec 28 2008, edited by Michel Marcus, Sep 22 2015

Examples

			Triangle begins:
1;
1,1;
1,1,2;
1,1,3,3;
1,1,4,4,6;
		

Crossrefs

A061554 is similar but with rows sorted into decreasing order.
Cf. A034868.
Cf. A053121. - Gary W. Adamson, Dec 28 2008
Cf. A103284.

Programs

  • Haskell
    import Data.List (sort)
    a107430 n k = a107430_tabl !! n !! k
    a107430_row n = a107430_tabl !! n
    a107430_tabl = map sort a007318_tabl
    -- Reinhard Zumkeller, May 26 2013
    
  • Magma
    /* As triangle */ [[Binomial(n,Floor(k/2)) : k in [0..n]]: n in [0.. 15]]; // Vincenzo Librandi, Sep 22 2015
    
  • Maple
    for n from 0 to 10 do sort([seq(binomial(n,k),k=0..n)]) od; # yields sequence in triangular form. - Emeric Deutsch, May 28 2005
  • Mathematica
    Flatten[ Table[ Sort[ Table[ Binomial[n, k], {k, 0, n}]], {n, 0, 12}]] (* Robert G. Wilson v, May 28 2005 *)
  • PARI
    for(n=0,20, for(k=0,n, print1(binomial(n,floor(k/2)), ", "))) \\ G. C. Greubel, May 22 2017

Formula

T(n,k) = C(n,floor(k/2)). - Paul Barry, Dec 15 2006; corrected by Philippe Deléham, Mar 15 2007
Sum_{k=0..n} T(n,k)*x^(n-k) = A127363(n), A127362(n), A127361(n), A126869(n), A001405(n), A000079(n), A127358(n), A127359(n), A127360(n) for x=-4,-3,-2,-1,0,1,2,3,4 respectively. - Philippe Deléham, Mar 29 2007

Extensions

More terms from Emeric Deutsch and Robert G. Wilson v, May 28 2005

A133443 a(n) = Sum_{k=0..n} C(n,floor(k/2))*(-1)^k*3^(n-k).

Original entry on oeis.org

1, 2, 8, 24, 84, 272, 920, 3040, 10180, 33840, 112968, 376224, 1254696, 4181088, 13939248, 46459584, 154873860, 516229040, 1720795880, 5735921440, 19119861304, 63732624672, 212442552528, 708140901184, 2360471473384, 7868234639072, 26227455730640
Offset: 0

Views

Author

Philippe Deléham, Nov 26 2007, Dec 07 2007

Keywords

Comments

Hankel transform is 4^n. Second binomial transform is A076035.

Crossrefs

Programs

  • Mathematica
    Table[Sum[Binomial[n,Floor[k/2]]*(-1)^k*3^(n-k),{k,0,n}],{n,0,20}] (* Vaclav Kotesovec, Oct 20 2012 *)

Formula

a(n) = Sum_{k=0..n} A053121(n,k)*A015518(k+1) = (-1)^n*A127362(n). G.f.: (1/sqrt(1-4*x^2))*(1-x*c(x^2))/(1-3*x*c(x^2)), where c(x) is the g.f. of Catalan numbers A000108.
Recurrence: 3*n*a(n) = 2*(5*n-3)*a(n-1) + 4*(3*n-1)*a(n-2) - 40*(n-2)*a(n-3). - Vaclav Kotesovec, Oct 20 2012
a(n) ~ 2*10^n/3^(n+1). - Vaclav Kotesovec, Oct 20 2012

Extensions

More terms from Vincenzo Librandi, May 25 2013
Showing 1-2 of 2 results.