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.

A005807 Sum of adjacent Catalan numbers.

Original entry on oeis.org

2, 3, 7, 19, 56, 174, 561, 1859, 6292, 21658, 75582, 266798, 950912, 3417340, 12369285, 45052515, 165002460, 607283490, 2244901890, 8331383610, 31030387440, 115948830660, 434542177290, 1632963760974, 6151850548776
Offset: 0

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Author

Keywords

Comments

The aerated sequence has Hankel transform F(n+2)*F(n+3) (A001654(n+2)). - Paul Barry, Nov 04 2008

Examples

			G.f. = 2 + 3*x+ 7*x^2 + 19*x^3 + 56*x^4 + 174*x^5 + 561*x^6 + 1859*x^7 + ...
		

References

  • D. E. Knuth, personal communication.
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Programs

  • Magma
    [((5*n+4)*Factorial(2*n))/(Factorial(n)*Factorial(n+2)): n in [0..30] ];  // Vincenzo Librandi, Aug 19 2011
    
  • Maple
    A005807List := proc(m) local A, P, n; A := [2,3]; P := [2,3];
    for n from 1 to m - 2 do P := ListTools:-PartialSums([op(P), P[-2]]);
    A := [op(A), P[-1]] od; A end: A005807List(25); # Peter Luschny, Mar 26 2022
  • Mathematica
    a[n_]:=Binomial[2*n, n]*(5*n+4)/(n+1)/(n+2); (* Vladimir Joseph Stephan Orlovsky, Dec 13 2008 *)
    a[ n_] := If[ n < 0, 0, CatalanNumber[n] + CatalanNumber[n + 1]]; (* Michael Somos, Jan 17 2015 *)
    Total/@Partition[CatalanNumber[Range[0,30]],2,1] (* Harvey P. Dale, Jun 21 2025 *)
  • PARI
    {a(n) = if( n<0, 0, binomial(2*n, n) * (5*n+4) / ((n+1) * (n+2)))};
    
  • Python
    from _future_ import division
    A005807_list, b = [], 2
    for n in range(10**3):
        A005807_list.append(b)
        b = b*(4*n+2)*(5*n+9)//((n+3)*(5*n+4)) # Chai Wah Wu, Jan 28 2016
  • Sage
    [catalan_number(i)+catalan_number(i+1) for i in range(0,25)] # Zerinvary Lajos, May 17 2009
    

Formula

a(n) = C(n)+C(n+1) = ((5*n+4)*(2*n)!)/(n!*(n+2)!).
G.f. A(x) satisfies x^2*A(x)^2 + (x-1)*A(x) + (x+2) = 0. - Michael Somos, Sep 11 2003
G.f.: (1-x - (1+x)*sqrt(1-4*x)) / (2*x^2) = (4+2*x) / (1-x + (1+x)*sqrt(1-4*x)). a(n)*(n+2)*(5*n-1) = a(n-1)*2*(2*n-1)*(5*n+4), n>0. - Michael Somos, Sep 11 2003
a(n) ~ 5*Pi^(-1/2)*n^(-3/2)*2^(2*n)*{1 - 93/40*n^-1 + 625/128*n^-2 - 10227/1024*n^-3 + 661899/32768*n^-4 ...}. - Joe Keane (jgk(AT)jgk.org), Sep 13 2002
G.f.: c(x)*(1+c(x))= (-1 +(1+x)*c(x))/x with the g.f. c(x) of A000108 (Catalan).
a(n) = binomial(2*n,n)/(n+1)*hypergeom([-1,n+1/2],[n+2],-4). - Peter Luschny, Aug 15 2012
D-finite with recurrence (n+2)*a(n) + (-3*n-2)*a(n-1) + 2*(-2*n+3)*a(n-2)=0. - R. J. Mathar, Dec 02 2012
0 = a(n)*(+16*a(n+1) + 38*a(n+2) - 18*a(n+3)) + a(n+1)*(-14*a(n+1) + 19*a(n+2) - 7*a(n+3)) + a(n+2)*(+a(n+2) + a(n+3)) for all n>=0. - Michael Somos, Jan 17 2015
0 = a(n)^2*(+368*a(n+1) - 182*a(n+2)) + a(n)*a(n+1)*(-306*a(n+1) + 317*a(n+2)) + a(n)*a(n+2)*(-77*a(n+2)) + a(n+1)^2*(-14*a(n+1) - 6*a(n+2)) + a(n+1)*a(n+2)*(+8*a(n+2)) for all n>=0. - Michael Somos, Jan 17 2015
E.g.f.: (BesselI(0,2*x) - (x - 1)*BesselI(1,2*x)/x)*exp(2*x). - Ilya Gutkovskiy, Jun 08 2016
G.f. with 1 prepended: Let E(x) = exp( Sum_{n >= 1} binomial(5*n,2*n)*x^n/n ). Then A(x) = ( x/series reversion of x*E(x) )^(1/5) = ( x/series reversion of x*D(x)^5 )^(1/5), where D(x) = 1 + 2*x + 23*x^2 + 371*x^3 + ... is the o.g.f. for A060941 .... Cf. A274052 and A274244. - Peter Bala, Jan 01 2020

Extensions

More terms from Joe Keane (jgk(AT)jgk.org), Feb 08 2000
Asymptotic series corrected and extended by Michael Somos, Sep 11 2003

A115127 Second (k=2) triangle of numbers related to totally asymmetric exclusion process (case alpha=1, beta=1).

Original entry on oeis.org

3, 6, 7, 10, 16, 19, 15, 30, 47, 56, 21, 50, 95, 146, 174, 28, 77, 170, 311, 471, 561, 36, 112, 280, 586, 1043, 1562, 1859, 45, 156, 434, 1015, 2044, 3564, 5291, 6292, 55, 210, 642, 1652, 3682, 7204, 12363, 18226, 21658, 66, 275, 915, 2562, 6230, 13392, 25623
Offset: 2

Views

Author

Wolfdieter Lang, Jan 13 2006

Keywords

Comments

This is the second floor (k=2) of a pyramid of numbers, called X(1,1,k=2,n,m) with n>=m+1>=2. One could use offset n>=1 and add a zero main diagonal.
The column sequences give for n>=m+1 and m=1..7: A000217, A005581, A024191, A115129, A115130, A115132, A115133.
The diagonal sequences give for M:=n-m=1..3: A071716, A071726, A115134.

Examples

			[3];[6,7];[10,16,19];[15,30,47,56];...
Main diagonal (n-m=1) example: a(3,2)= 7 = 5 + 2 because
A115126(3,2)=5 and A115126(2,2)=2.
Subdiagonal (n-m>1) example: a(4,2)= 16 = 9 + 7 because
A115126(4,2)=9 and a(3,2)=7.
		

Crossrefs

Row sums give A115128.

Formula

a(n,m)= b(n,m) + b(n-1,m) with b(n,m):=A115126(n,m) if n=m+1 (main diagonal), A115126(n,m) + a(n,-1,m) if n>m+1 (subdiagonals) and 0 if n

A167422 Expansion of (1+x)*c(x), c(x) the g.f. of A000108.

Original entry on oeis.org

1, 2, 3, 7, 19, 56, 174, 561, 1859, 6292, 21658, 75582, 266798, 950912, 3417340, 12369285, 45052515, 165002460, 607283490, 2244901890, 8331383610, 31030387440, 115948830660, 434542177290, 1632963760974, 6151850548776
Offset: 0

Author

Paul Barry, Nov 03 2009

Keywords

Comments

Hankel transform is A167423.
Apparently a(n) = A071716(n) if n>1. - R. J. Mathar, Nov 12 2009

Programs

  • Maple
    A167422List := proc(m) local A, P, n; A := [1, 2]; P := [1];
    for n from 1 to m - 2 do P := ListTools:-PartialSums([op(P), A[-1]]);
    A := [op(A), P[-1]] od; A end: A167422List(26); # Peter Luschny, Mar 24 2022
  • Mathematica
    Table[If[n < 2, n + 1, Binomial[2 n, n]/(n + 1) + Binomial[2 (n - 1), n - 1]/n], {n, 0, 25}] (* Michael De Vlieger, Oct 05 2015 *)
    CoefficientList[Series[(1 + t)*(1 - Sqrt[1 - 4*t])/(2*t), {t, 0, 50}], t] (* G. C. Greubel, Jun 12 2016 *)
  • PARI
    a(n) = if (n<2, n+1, binomial(2*n, n)/(n+1) + binomial(2*(n-1), n-1)/n);
    vector(50, n, a(n-1)) \\ Altug Alkan, Oct 04 2015

Formula

a(n) = Sum_{k=0..n} A000108(k)*C(1,n-k).
a(0)= 1, a(n) = A005807(n-1) for n>0. - Philippe Deléham, Nov 25 2009
(n+1)*a(n) +(-3*n+1)*a(n-1) +2*(-2*n+5)*a(n-2)=0, for n>2. - R. J. Mathar, Feb 10 2015
-(n+1)*(5*n-6)*a(n) +2*(5*n-1)*(2*n-3)*a(n-1)=0. - R. J. Mathar, Feb 10 2015
The o.g.f. A(x) satisfies [x^n] A(x)^(5*n) = binomial(5*n,2*n) = A001450(n). Cf. A182959. - Peter Bala, Oct 04 2015

A352680 Array read by ascending antidiagonals. A family of Catalan-like sequences. A(n, k) = [x^k] ((n - 1)*x + 1)*(1 - sqrt(1 - 4*x))/(2*x).

Original entry on oeis.org

1, 1, 0, 1, 1, 1, 1, 2, 2, 3, 1, 3, 3, 5, 9, 1, 4, 4, 7, 14, 28, 1, 5, 5, 9, 19, 42, 90, 1, 6, 6, 11, 24, 56, 132, 297, 1, 7, 7, 13, 29, 70, 174, 429, 1001, 1, 8, 8, 15, 34, 84, 216, 561, 1430, 3432, 1, 9, 9, 17, 39, 98, 258, 693, 1859, 4862, 11934, 1, 10, 10, 19, 44, 112, 300, 825, 2288, 6292, 16796, 41990
Offset: 0

Author

Peter Luschny, Mar 27 2022

Keywords

Examples

			Array starts:
n\k 0, 1,  2,  3,  4,   5,   6,    7,    8,     9, ...
------------------------------------------------------
[0] 1, 0,  1,  3,  9,  28,  90,  297, 1001,  3432, ... A071724
[1] 1, 1,  2,  5, 14,  42, 132,  429, 1430,  4862, ... A000108
[2] 1, 2,  3,  7, 19,  56, 174,  561, 1859,  6292, ... A071716
[3] 1, 3,  4,  9, 24,  70, 216,  693, 2288,  7722, ... A038629
[4] 1, 4,  5, 11, 29,  84, 258,  825, 2717,  9152, ... A352681
[5] 1, 5,  6, 13, 34,  98, 300,  957, 3146, 10582, ...
[6] 1, 6,  7, 15, 39, 112, 342, 1089, 3575, 12012, ...
[7] 1, 7,  8, 17, 44, 126, 384, 1221, 4004, 13442, ...
[8] 1, 8,  9, 19, 49, 140, 426, 1353, 4433, 14872, ...
[9] 1, 9, 10, 21, 54, 154, 468, 1485, 4862, 16302, ...
.
Seen as a triangle:
[0] 1;
[1] 1, 0;
[1] 1, 1, 1;
[2] 1, 2, 2,  3;
[3] 1, 3, 3,  5,  9;
[4] 1, 4, 4,  7, 14, 28;
[5] 1, 5, 5,  9, 19, 42,  90;
[6] 1, 6, 6, 11, 24, 56, 132, 297;
		

Crossrefs

Diagonals: A077587 (main), A271823.
Compare A352682 for a similar array based on the Bell numbers.

Programs

  • Julia
    # Compare with the Julia function A352686Row.
    function A352680Row(n, len)
        a = BigInt(n)
        P = BigInt[1]; T = BigInt[1]
        for k in 0:len-1
            T = push!(T, a)
            P = cumsum(push!(P, a))
            a = P[end]
        end
    T end
    for n in 0:9 println(A352680Row(n, 9)) end
  • Maple
    for n from 0 to 9 do
        ogf := ((n - 1)*x + 1)*(1 - sqrt(1 - 4*x))/(2*x);
        ser := series(ogf, x, 12):
        print(seq(coeff(ser, x, k), k = 0..9)); od:
    # Alternative:
    alias(PS = ListTools:-PartialSums):
    CatalanRow := proc(n, len) local a, k, P, R;
    a := n; P := [1]; R := [1];
    for k from 0 to len-1 do
        R := [op(R), a]; P := PS([op(P), a]); a := P[-1] od;
    R end: seq(lprint(CatalanRow(n, 9)), n = 0..9);
    # Recurrence:
    A := proc(n, k) option remember: if k < 3 then [1, n, n + 1][k + 1] else
    A(n, k-1)*((6 - 4*k)*(n - 3 + k*(3 + n)))/((1 + k)*(6 - k*(3 + n))) fi end:
    seq(print(seq(A(n, k), k = 0..9)), n = 0..9);
  • Mathematica
    T[n_, 0] := 1;
    T[n_, k_] := (n - 1) CatalanNumber[k - 1] + CatalanNumber[k];
    Table[T[n, k], {n, 0, 9}, {k, 0, 9}] // TableForm

Formula

A(n, k) = (n-1)*CatalanNumber(k-1) + CatalanNumber(k) for n >= 0 and k >= 1, A(n, 0) = 1. (Cf. A352682.)
D-finite with recurrence: A(n, k) = A(n, k-1)*((6 - 4*k)*(n - 3 + k*(3 + n)))/((1 + k)*(6 - k*(3 + n))) for k >= 3, otherwise 1, n, n + 1 for k = 0, 1, 2.
Given a list T let PS(T) denote the list of partial sums of T. Given two list S and T let [S, T] denote the concatenation of the lists. Further let P[end] denote the last element of the list P. Row n of the array A with length k can be computed by the following procedure:
A = [n], P = [1], R = [1];
Repeat k times: R = [R, A], P = PS([P, A]), A = [P[end]];
Return R.

A000778 a(n) = Catalan(n) + Catalan(n+1) - 1.

Original entry on oeis.org

1, 2, 6, 18, 55, 173, 560, 1858, 6291, 21657, 75581, 266797, 950911, 3417339, 12369284, 45052514, 165002459, 607283489, 2244901889, 8331383609, 31030387439, 115948830659, 434542177289, 1632963760973, 6151850548775, 23229299473603, 87900903988155
Offset: 0

Keywords

Crossrefs

Cf. A000108.
Equals A005807(n) - 1. Cf. A071716.

Programs

  • Mathematica
    Table[CatalanNumber[n] + CatalanNumber[n + 1] - 1, {n, 0, 200}] (* T. D. Noe, Jun 20 2012 *)

Formula

D-finite with recurrence (n+2)*a(n) +(-5*n-4)*a(n-1) +(3*n+4)*a(n-2) +(5*n-16)*a(n-3) +2*(-2*n+7)*a(n-4)=0. - R. J. Mathar, Jun 17 2020

A350584 Triangle read by rows, T(n, k) = [x^k] ((2*x^3 - 3*x^2 - x + 1)/(1 - x)^(n + 2)), for n >= 1 and 0 <= k < n.

Original entry on oeis.org

1, 1, 3, 1, 4, 7, 1, 5, 12, 19, 1, 6, 18, 37, 56, 1, 7, 25, 62, 118, 174, 1, 8, 33, 95, 213, 387, 561, 1, 9, 42, 137, 350, 737, 1298, 1859, 1, 10, 52, 189, 539, 1276, 2574, 4433, 6292, 1, 11, 63, 252, 791, 2067, 4641, 9074, 15366, 21658
Offset: 1

Author

Peter Luschny, Mar 27 2022

Keywords

Examples

			Triangle starts:
[1] [1]
[2] [1,  3]
[3] [1,  4,  7]
[4] [1,  5, 12,  19]
[5] [1,  6, 18,  37,  56]
[6] [1,  7, 25,  62, 118,  174]
[7] [1,  8, 33,  95, 213,  387,  561]
[8] [1,  9, 42, 137, 350,  737, 1298, 1859]
[9] [1, 10, 52, 189, 539, 1276, 2574, 4433, 6292]
		

Crossrefs

A280891 (row sums), A135339 (alternating row sums), A005807 or A071716 (main diagonal).

Programs

  • Maple
    # Compare the analogue algorithm for the Bell triangle in A046937.
    A350584Triangle := proc(len) local A, P, T, n; A := [2]; P := [1]; T := [[1]];
    for n from 1 to len-1 do P := ListTools:-PartialSums([op(P), A[-1]]);
    A := P; T := [op(T), P] od; T end:
    A350584Triangle(10): ListTools:-Flatten(%);
    # Alternative:
    ogf := n -> (2*x^3 - 3*x^2 - x + 1)/(1 - x)^(n + 2):
    ser := n -> series(ogf(n), x, n):
    row := n -> seq(coeff(ser(n), x, k), k = 0..n-1):
    seq(row(n), n = 1..10);

A071717 Expansion of (1 + x^2*C)*C^2, where C = (1 - sqrt(1-4*x))/(2*x) is g.f. for Catalan numbers, A000108.

Original entry on oeis.org

1, 2, 6, 17, 51, 160, 519, 1727, 5863, 20228, 70720, 250002, 892126, 3209328, 11626385, 42378075, 155307615, 571925820, 2115257100, 7853744910, 29263124250, 109384710240, 410075910270, 1541481197334, 5808790935126
Offset: 0

Author

N. J. A. Sloane, Jun 06 2002

Keywords

Crossrefs

Programs

  • Maple
    seq(coeff(series( ((1-x-3*x^2) -(1+x-x^2)*sqrt(1-4*x))/(2*x^2) , x, n+1), x, n), n = 0..30); # G. C. Greubel, May 30 2020
  • Mathematica
    With[{$MaxExtraPrecision = 1000}, CoefficientList[Series[(1 + x^2*#)*#^2 &[(1 - (1 - 4 x)^(1/2))/(2 x)], {x, 0, 24}], x]] (* Michael De Vlieger, May 30 2020 *)
  • Sage
    def A071717_list(prec):
        P. = PowerSeriesRing(ZZ, prec)
        return P( ((1-x-3*x^2) -(1+x-x^2)*sqrt(1-4*x))/(2*x^2) ).list()
    A071717_list(30) # G. C. Greubel, May 30 2020

Formula

Conjecture: (n+2)*a(n) +(-3*n-2)*a(n-1) +(-5*n+8)*a(n-2) +2*(2*n-7)*a(n-3)=0. - R. J. Mathar, Aug 25 2013
G.f.: ( (1 -x -3*x^2) - (1 +x -x^2)*sqrt(1-4*x) )/(2*x^2). - G. C. Greubel, May 30 2020
Showing 1-7 of 7 results.