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 1-7 of 7 results.

A268148 A double binomial sum involving absolute values.

Original entry on oeis.org

0, 8, 768, 30720, 917504, 23592960, 553648128, 12213813248, 257698037760, 5257039970304, 104453604638720, 2031897488130048, 38843546786070528, 731834939447705600, 13618885273168379904, 250760427251989217280, 4574792530279968800768, 82788987402808467652608
Offset: 0

Views

Author

Richard P. Brent, Jan 27 2016

Keywords

Comments

A fast algorithm follows from Theorem 5 of Brent et al. article.

Crossrefs

Programs

  • PARI
    a(n) = sum(k=-n,n, sum(l=-n,n, binomial(2*n, n+k)*binomial(2*n, n+l)*abs(k^2 - l^2)^2));
    
  • PARI
    concat(0, Vec(8*x*(1+48*x)/(1-16*x)^3 + O(x^20))) \\ Colin Barker, Feb 11 2016

Formula

a(n) = Sum_{k=-n..n} (Sum_{l=-n..n} binomial(2*n, n+k)*binomial(2*n, n+l)*abs(k^2 - l^2)^2).
From Colin Barker, Feb 11 2016: (Start)
a(n) = 2^(4*n-1)*n*(2*n-1).
a(n) = 48*a(n-1)-768*a(n-2)+4096*a(n-3) for n>2.
G.f.: 8*x*(1+48*x) / (1-16*x)^3.
(End)

A268147 A double binomial sum involving absolute values.

Original entry on oeis.org

0, 16, 512, 12288, 262144, 5242880, 100663296, 1879048192, 34359738368, 618475290624, 10995116277760, 193514046488576, 3377699720527872, 58546795155816448, 1008806316530991104, 17293822569102704640, 295147905179352825856, 5017514388048998039552
Offset: 0

Views

Author

Richard P. Brent, Jan 27 2016

Keywords

Comments

A fast algorithm follows from Theorem 1 of Brent et al. article.

Crossrefs

Programs

  • Maple
    a:= proc(n) option remember;
          16*`if`(n<2, n, n*a(n-1)/(n-1))
        end:
    seq(a(n), n=0..20);  # Alois P. Heinz, Jan 29 2016
  • Mathematica
    Table[n*16^n, {n, 0, 20}] (* Jean-François Alcover, Oct 24 2016 *)
    LinearRecurrence[{32,-256},{0,16},20] (* Harvey P. Dale, Jul 19 2018 *)
  • PARI
    a(n) = sum(k=-n,n, sum(l=-n,n,binomial(2*n, n+k)*binomial(2*n, n+l)*abs(k-l)^2));
    
  • PARI
    concat(0, Vec(16*x/(1-16*x)^2 + O(x^20))) \\ Colin Barker, Feb 11 2016
    
  • PARI
    a(n)=n*16^n \\ Charles R Greathouse IV, May 10 2016

Formula

a(n) = Sum_{k=-n..n} (Sum_{l=-n..n} binomial(2*n, n+k)*binomial(2*n, n+l)*abs(k-l)^2).
From Colin Barker, Feb 11 2016: (Start)
a(n) = n*16^n.
a(n) = 32*a(n-1)-256*a(n-2) for n>1.
G.f.: 16*x / (1-16*x)^2.
(End)

A268150 A double binomial sum involving absolute values.

Original entry on oeis.org

0, 8, 2496, 177120, 7616000, 255780000, 7410154752, 194544814464, 4760448675840, 110493063252000, 2461297261280000, 53051182041906048, 1113060644163127296, 22833886572836393600, 459594580755139200000, 9100826722891800000000, 177680489488222659379200, 3426237501864596491802400
Offset: 0

Views

Author

Richard P. Brent, Jan 27 2016

Keywords

Comments

A fast algorithm follows from Lemma 1 of Brent et al. article.

Crossrefs

Programs

  • Maple
    A268150 := proc(n)
        add( add( binomial(2*n,n+k)*binomial(2*n,n+l)*abs(k^2-l^2)^3,l=-n..n),k=-n..n) ;
    end proc:
    seq(A268150(n),n=0..10) ; # R. J. Mathar, Feb 27 2023
  • PARI
    a(n) = sum(k=-n,n, sum(l=-n,n, binomial(2*n, n+k)*binomial(2*n, n+l)*abs(k^2 - l^2)^3));

Formula

a(n) = Sum_{k=-n..n} (Sum_{l=-n..n} binomial(2*n, n+k)*binomial(2*n, n+l)*abs(k^2 - l^2)^3).
Conjecture D-finite with recurrence -(4621*n-8921)*(n-1)^2*a(n) +4*(148256*n^3 -1055204*n^2 +2794799*n -2529792)*a(n-1) -64*(32443*n- 32400)*(2*n-3)*(2*n-5)*a(n-2)=0. - R. J. Mathar, Feb 27 2023

A268152 A double binomial sum involving absolute values.

Original entry on oeis.org

0, 8, 8832, 1228800, 79364096, 3562536960, 129276837888, 4079413624832, 116608362086400, 3096396542509056, 77661255048888320, 1861218099127123968, 42980384518787039232, 962362945373732864000, 20993511648589057622016, 447858123072052742062080, 9371462498278516088373248
Offset: 0

Views

Author

Richard P. Brent, Jan 27 2016

Keywords

Comments

A fast algorithm follows from Theorem 5 of Brent et al. article.

Crossrefs

Programs

  • PARI
    a(n) = sum(k=-n,n,sum(l=-n,n, binomial(2*n, n+k)*binomial(2*n, n+l)*abs(k^2 - l^2)^4));
    
  • PARI
    concat(0, Vec(8*x*(1+1024*x+67840*x^2+417792*x^3)/(1-16*x)^5 + O(x^20))) \\ Colin Barker, Feb 11 2016

Formula

a(n) = Sum_{k=-n..n} (Sum_{l=-n..n} binomial(2*n, n+k)*binomial(2*n, n+l)*abs(k^2 - l^2)^4).
From Colin Barker, Feb 11 2016: (Start)
a(n) = 4^(2*n-1)*n*(36*n^3-84*n^2+67*n-17).
a(n) = 80*a(n-1)-2560*a(n-2)+40960*a(n-3)-327680*a(n-4)+1048576*a(n-5) for n>4.
G.f.: 8*x*(1+1024*x+67840*x^2+417792*x^3) / (1-16*x)^5.
(End)

A166335 Exponential Riordan array [1+x*sinh(x), x].

Original entry on oeis.org

1, 0, 1, 2, 0, 1, 0, 6, 0, 1, 4, 0, 12, 0, 1, 0, 20, 0, 20, 0, 1, 6, 0, 60, 0, 30, 0, 1, 0, 42, 0, 140, 0, 42, 0, 1, 8, 0, 168, 0, 280, 0, 56, 0, 1, 0, 72, 0, 504, 0, 504, 0, 72, 0, 1, 10, 0, 360, 0, 1260, 0, 840, 0, 90, 0, 1
Offset: 0

Views

Author

Paul Barry, Oct 12 2009

Keywords

Examples

			Triangle begins
1,
0, 1,
2, 0, 1,
0, 6, 0, 1,
4, 0, 12, 0, 1,
0, 20, 0, 20, 0, 1,
6, 0, 60, 0, 30, 0, 1,
0, 42, 0, 140, 0, 42, 0, 1,
8, 0, 168, 0, 280, 0, 56, 0, 1,
0, 72, 0, 504, 0, 504, 0, 72, 0, 1,
10, 0, 360, 0, 1260, 0, 840, 0, 90, 0, 1
		

Crossrefs

Row sums are A131056. Diagonal sums are A166336. Central coefficients are A166337.

Programs

  • Mathematica
    (* The function RiordanArray is defined in A256893. *)
    RiordanArray[1 + # Sinh[#]&, #&, 11, True] // Flatten (* Jean-François Alcover, Jul 19 2019 *)

Formula

Number triangle T(n,k)=[k<=n]*C(n,k)*((n-k)+0^((n-k)/2))(1+(-1)^(n-k))/2.

A268149 A double binomial sum involving absolute values.

Original entry on oeis.org

0, 24, 1120, 33264, 823680, 18475600, 389398464, 7862853600, 153876579840, 2940343837200, 55138611528000, 1018383898440480, 18574619721465600, 335240928272918304, 5996573430996184960, 106438123408375281600, 1876607120325212706816, 32891715945378106711440
Offset: 0

Views

Author

Richard P. Brent, Jan 27 2016

Keywords

Comments

A fast algorithm follows from Theorem 1 of Brent et al. article.

Crossrefs

Programs

  • PARI
    a(n) = sum(k=-n,n, sum(l=-n,n, binomial(2*n, n+k)*binomial(2*n, n+l)*abs(k-l)^3));

Formula

a(n) = Sum_{k=-n..n} (Sum_{l=-n..n} binomial(2*n, n+k)*binomial(2*n, n+l)*abs(k-l)^3).
Conjecture D-finite with recurrence (2*n-1)*(n-1)*a(n) +2*(-22*n^2+27*n-36)*a(n-1) +12*(4*n-5)*(4*n-7)*a(n-2)=0. - R. J. Mathar, Feb 27 2023

A268151 A double binomial sum involving absolute values.

Original entry on oeis.org

0, 40, 2816, 104448, 3014656, 76021760, 1761607680, 38520487936, 807453851648, 16389595201536, 324355930193920, 6289206510878720, 119908340078739456, 2254051613498933248, 41865462136036130816, 769575104325070356480, 14019525496019259228160, 253384476596474400997376
Offset: 0

Views

Author

Richard P. Brent, Jan 27 2016

Keywords

Comments

A fast algorithm follows from Theorem 1 of Brent et al. article.

Crossrefs

Programs

  • Mathematica
    LinearRecurrence[{48,-768,4096},{0,40,2816},20] (* Harvey P. Dale, Apr 28 2022 *)
  • PARI
    a(n) = sum(k=-n,n, sum(l=-n,n, binomial(2*n, n+k)*binomial(2*n, n+l)*abs(k-l)^4));
    
  • PARI
    concat(0, Vec(8*x*(5+112*x)/(1-16*x)^3 + O(x^20))) \\ Colin Barker, Feb 11 2016

Formula

a(n) = Sum_{k=-n..n} (Sum_{l=-n..n} binomial(2*n, n+k)*binomial(2*n, n+l)*abs(k-l)^4).
From Colin Barker, Feb 11 2016: (Start)
a(n) = 2^(4*n-1)*n*(6*n-1).
a(n) = 48*a(n-1)-768*a(n-2)+4096*a(n-3) for n>2.
G.f.: 8*x*(5+112*x) / (1-16*x)^3.
(End)
Showing 1-7 of 7 results.