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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A158835 Triangle, read by rows, that transforms diagonals in the array A158825 of coefficients of successive iterations of x*C(x) where C(x) is the Catalan function (A000108).

Original entry on oeis.org

1, 1, 1, 4, 2, 1, 27, 11, 3, 1, 254, 94, 21, 4, 1, 3062, 1072, 217, 34, 5, 1, 45052, 15212, 2904, 412, 50, 6, 1, 783151, 257777, 47337, 6325, 695, 69, 7, 1, 15712342, 5074738, 906557, 116372, 12035, 1082, 91, 8, 1, 357459042, 113775490, 19910808, 2483706
Offset: 1

Views

Author

Paul D. Hanna, Mar 28 2009, Mar 29 2009

Keywords

Comments

Conjecture: n-th reversed row polynomial is t_n where we start with vector v of fixed length m with elements v_i = 1, then set t := v and for i=1..m-1, for j=1..i, for k=j+1..i+1 apply v_k := v_k + z*v_{k-1} and t_{i+1} := v_{i+1} (after ending each cycle for j). - Mikhail Kurkov, Sep 03 2024

Examples

			Triangle T begins:
  1;
  1,1;
  4,2,1;
  27,11,3,1;
  254,94,21,4,1;
  3062,1072,217,34,5,1;
  45052,15212,2904,412,50,6,1;
  783151,257777,47337,6325,695,69,7,1;
  15712342,5074738,906557,116372,12035,1082,91,8,1;
  357459042,113775490,19910808,2483706,246596,20859,1589,116,9,1;
  9094926988,2861365660,492818850,60168736,5801510,470928,33747,2232,144,10,1;
  ...
Array A158825 of coefficients in iterations of x*C(x) begins:
  1,1,2,5,14,42,132,429,1430,4862,16796,58786,208012,742900,...;
  1,2,6,21,80,322,1348,5814,25674,115566,528528,2449746,...;
  1,3,12,54,260,1310,6824,36478,199094,1105478,6227712,...;
  1,4,20,110,640,3870,24084,153306,993978,6544242,43652340,...;
  1,5,30,195,1330,9380,67844,500619,3755156,28558484,...;
  1,6,42,315,2464,19852,163576,1372196,11682348,100707972,...;
  1,7,56,476,4200,38052,351792,3305484,31478628,303208212,...;
  1,8,72,684,6720,67620,693048,7209036,75915708,807845676,...;
  1,9,90,945,10230,113190,1273668,14528217,167607066,...;
  1,10,110,1265,14960,180510,2212188,27454218,344320262,...;
  ...
This triangle transforms diagonals of A158825 into each other:
T*A158831 = A158832; T*A158832 = A158833; T*A158833 = A158834;
where:
A158831 = [1,1,6,54,640,9380,163576,3305484,...];
A158832 = [1,2,12,110,1330,19852,351792,7209036,...];
A158833 = [1,3,20,195,2464,38052,693048,14528217,...];
A158834 = [1,4,30,315,4200,67620,1273668,27454218,...].
		

Crossrefs

Cf. columns: A158836, A158837, A158838, A158839, row sums: A158840.

Programs

  • PARI
    {T(n, k)=local(F=x, CAT=serreverse(x-x^2+x*O(x^(n+2))), M, N, P, m=max(n, k)); M=matrix(m+2, m+2, r, c, F=x; for(i=1, r+c-2, F=subst(F, x, CAT)); polcoeff(F, c)); N=matrix(m+1, m+1, r, c, M[r, c]); P=matrix(m+1, m+1, r, c, M[r+1, c]); (P~*N~^-1)[n+1, k+1]}
    for(n=0,12,for(k=0,n,print1(T(n,k),", "));print(""))

Extensions

Edited by N. J. A. Sloane, Oct 04 2010, to make entries, offset, b-file and link to b-file all consistent.

A158831 A diagonal in the array A158825 of coefficients of successive iterations of x*C(x), where C(x) is the Catalan function (A000108).

Original entry on oeis.org

1, 1, 6, 54, 640, 9380, 163576, 3305484, 75915708, 1952409954, 55573310936, 1734182983962, 58863621238500, 2159006675844616, 85088103159523296, 3585740237981536700, 160894462797493581048, 7658326127259130753070
Offset: 1

Views

Author

Paul D. Hanna, Mar 28 2009

Keywords

Comments

Triangle A158835 transforms this sequence into A158832, the next diagonal in A158825.

Examples

			Table of coefficients in the i-th iteration of x*Catalan(x):
(1);
1,(1),2,5,14,42,132,429,1430,4862,16796,58786,208012,...;
1,2,(6),21,80,322,1348,5814,25674,115566,528528,2449746,...;
1,3,12,(54),260,1310,6824,36478,199094,1105478,6227712,...;
1,4,20,110,(640),3870,24084,153306,993978,6544242,43652340,...;
1,5,30,195,1330,(9380),67844,500619,3755156,28558484,...;
1,6,42,315,2464,19852,(163576),1372196,11682348,100707972,...;
1,7,56,476,4200,38052,351792,(3305484),31478628,303208212,...;
1,8,72,684,6720,67620,693048,7209036,(75915708),807845676,...;
1,9,90,945,10230,113190,1273668,14528217,167607066,(1952409954),...; ...
where terms in parenthesis form the initial terms of this sequence.
		

Crossrefs

Programs

  • Mathematica
    nmax = 18;
    g[x_] := Module[{y}, Expand[Normal[(1 - Sqrt[1 - 4*y])/2 + O[y]^(nmax+2)] /. y -> x][[1 ;; nmax+1]]];
    T = Table[Nest[g, x, n] // CoefficientList[#, x]& // Rest, {n, 1, nmax+1}];
    Prepend[Diagonal[T, 1], 1] (* Jean-François Alcover, Jul 13 2018 *)
  • PARI
    {a(n)=local(F=serreverse(x-x^2+O(x^(n+2))),G=x); for(i=1,n-1,G=subst(F,x,G));polcoeff(G,n)}

A158832 Main diagonal in the array A158825 of coefficients of successive iterations of x*C(x), where C(x) is the Catalan function (A000108).

Original entry on oeis.org

1, 2, 12, 110, 1330, 19852, 351792, 7209036, 167607066, 4357308098, 125219900520, 3941126688798, 134808743674176, 4979127855477336, 197480359402576304, 8370550907396970684, 377599345119560766534, 18061714498169627460982
Offset: 1

Views

Author

Paul D. Hanna, Mar 28 2009

Keywords

Comments

Triangle A158835 transforms A158831 into this sequence, where A158831 is the previous diagonal in A158825.
Triangle A158835 transforms this sequence into A158833, the next diagonal in A158825.

Examples

			Array of coefficients in the i-th iteration of x*Catalan(x):
(1),1,2,5,14,42,132,429,1430,4862,16796,58786,208012,...;
1,(2),6,21,80,322,1348,5814,25674,115566,528528,2449746,...;
1,3,(12),54,260,1310,6824,36478,199094,1105478,6227712,...;
1,4,20,(110),640,3870,24084,153306,993978,6544242,43652340,...;
1,5,30,195,(1330),9380,67844,500619,3755156,28558484,...;
1,6,42,315,2464,(19852),163576,1372196,11682348,100707972,...;
1,7,56,476,4200,38052,(351792),3305484,31478628,303208212,...;
1,8,72,684,6720,67620,693048,(7209036),75915708,807845676,...;
1,9,90,945,10230,113190,1273668,14528217,(167607066),...;
1,10,110,1265,14960,180510,2212188,27454218,344320262,(4357308098),...; ...
where terms in parenthesis form the initial terms of this sequence.
		

Crossrefs

Programs

  • Mathematica
    a[n_] := Module[{x, F, G}, F = InverseSeries[x - x^2 + O[x]^(n+2)]; G = x; For[i = 1, i <= n, i++, G = (F /. x -> G)]; Coefficient[G, x, n]];
    Array[a, 18] (* Jean-François Alcover, Jul 13 2018, from PARI *)
  • PARI
    {a(n)=local(F=serreverse(x-x^2+O(x^(n+2))),G=x); for(i=1,n,G=subst(F,x,G));polcoeff(G,n)}

A158833 A diagonal in the array A158825 of coefficients of successive iterations of x*C(x), where C(x) is the Catalan function (A000108).

Original entry on oeis.org

1, 3, 20, 195, 2464, 38052, 693048, 14528217, 344320262, 9100230282, 265305808404, 8456446272144, 292528760419440, 10913859037065560, 436812586581170976, 18668379209883807385, 848499254768957476312
Offset: 1

Views

Author

Paul D. Hanna, Mar 28 2009

Keywords

Comments

Triangle A158835 transforms A158832 into this sequence, where A158832 is the previous diagonal in A158825.
Triangle A158835 transforms this sequence into A158834, the next diagonal in A158825.

Examples

			Array of coefficients in the i-th iteration of x*Catalan(x):
1,1,2,5,14,42,132,429,1430,4862,16796,58786,208012,...;
(1),2,6,21,80,322,1348,5814,25674,115566,528528,2449746,...;
1,(3),12,54,260,1310,6824,36478,199094,1105478,6227712,...;
1,4,(20),110,640,3870,24084,153306,993978,6544242,43652340,...;
1,5,30,(195),1330,9380,67844,500619,3755156,28558484,...;
1,6,42,315,(2464),19852,163576,1372196,11682348,100707972,...;
1,7,56,476,4200,(38052),351792,3305484,31478628,303208212,...;
1,8,72,684,6720,67620,(693048),7209036,75915708,807845676,...;
1,9,90,945,10230,113190,1273668,(14528217),167607066,...;
1,10,110,1265,14960,180510,2212188,27454218,(344320262),...;
1,11,132,1650,21164,276562,3666520,49181418,666200106,(9100230282),...; ...
where terms in parenthesis form the initial terms of this sequence.
		

Crossrefs

Programs

  • Mathematica
    a[n_] := Module[{x, F, G}, F = InverseSeries[x - x^2 + O[x]^(n+2)]; G = x; For[i = 1, i <= n+1, i++, G = (F /. x -> G)]; Coefficient[G, x, n]];
    Array[a, 17] (* Jean-François Alcover, Jul 13 2018, from PARI *)
  • PARI
    {a(n)=local(F=serreverse(x-x^2+O(x^(n+2))),G=x); for(i=1,n+1,G=subst(F,x,G));polcoeff(G,n)}

A158834 A diagonal in the array A158825 of coefficients of successive iterations of x*C(x), where C(x) is the Catalan function (A000108).

Original entry on oeis.org

1, 4, 30, 315, 4200, 67620, 1273668, 27454218, 666200106, 17968302638, 533188477536, 17261808531552, 605452449574320, 22870569475477112, 925663441858807096, 39964465820186753753, 1833332492818402014474
Offset: 1

Views

Author

Paul D. Hanna, Mar 28 2009

Keywords

Comments

Triangle A158835 transforms A158833 into this sequence, where A158833 is the previous diagonal in A158825.

Examples

			Array of coefficients in the i-th iteration of x*Catalan(x):
1,1,2,5,14,42,132,429,1430,4862,16796,58786,208012,...;
1,2,6,21,80,322,1348,5814,25674,115566,528528,2449746,...;
(1),3,12,54,260,1310,6824,36478,199094,1105478,6227712,...;
1,(4),20,110,640,3870,24084,153306,993978,6544242,43652340,...;
1,5,(30),195,1330,9380,67844,500619,3755156,28558484,...;
1,6,42,(315),2464,19852,163576,1372196,11682348,100707972,...;
1,7,56,476,(4200),38052,351792,3305484,31478628,303208212,...;
1,8,72,684,6720,(67620),693048,7209036,75915708,807845676,...;
1,9,90,945,10230,113190,(1273668),14528217,167607066,...;
1,10,110,1265,14960,180510,2212188,(27454218),344320262,...;
1,11,132,1650,21164,276562,3666520,49181418,(666200106),...;
1,12,156,2106,29120,409682,5841836,84218134,1225314662,(17968302638),...; ...
where terms in parenthesis form the initial terms of this sequence.
		

Crossrefs

Programs

  • Mathematica
    a[n_] := Module[{x, F, G}, F = InverseSeries[x - x^2 + O[x]^(n+2)]; G = x; For[i = 1, i <= n+2, i++, G = (F /. x -> G)]; Coefficient[G, x, n]];
    Array[a, 17] (* Jean-François Alcover, Jul 13 2018, from PARI *)
  • PARI
    {a(n)=local(F=serreverse(x-x^2+O(x^(n+2))),G=x); for(i=1,n+2,G=subst(F,x,G));polcoeff(G,n)}

A158829 Antidiagonal sums of square array A158825, in which row n lists the coefficients of the n-th iteration of x*C(x), where C(x) is the Catalan function (A000108).

Original entry on oeis.org

1, 1, 2, 5, 15, 52, 202, 861, 3972, 19648, 103500, 577443, 3396804, 20988116, 135770140, 916936351, 6449233093, 47137434787, 357331341987, 2804582808108, 22754919576652, 190578011064394, 1645490708244886, 14629351150837605
Offset: 1

Views

Author

Paul D. Hanna, Mar 28 2009

Keywords

Crossrefs

Programs

  • PARI
    {a(n)=local(F=serreverse(x-x^2+O(x^(n+1))),G=x,ADS=0); for(k=1,n,G=x;for(i=1,n-k,G=subst(F,x,G));ADS=ADS+polcoeff(G,k));ADS}

A158830 Triangle, read by rows n>=1, where row n is the n-th differences of column n of array A158825, where the g.f. of row n of A158825 is the n-th iteration of x*Catalan(x).

Original entry on oeis.org

1, 1, 0, 2, 0, 0, 5, 1, 0, 0, 14, 10, 0, 0, 0, 42, 70, 8, 0, 0, 0, 132, 424, 160, 4, 0, 0, 0, 429, 2382, 1978, 250, 1, 0, 0, 0, 1430, 12804, 19508, 6276, 302, 0, 0, 0, 0, 4862, 66946, 168608, 106492, 15674, 298, 0, 0, 0, 0, 16796, 343772, 1337684, 1445208, 451948
Offset: 1

Views

Author

Paul D. Hanna, Mar 28 2009

Keywords

Examples

			Triangle begins:
.1;
.1,0;
.2,0,0;
.5,1,0,0;
.14,10,0,0,0;
.42,70,8,0,0,0;
.132,424,160,4,0,0,0;
.429,2382,1978,250,1,0,0,0;
.1430,12804,19508,6276,302,0,0,0,0;
.4862,66946,168608,106492,15674,298,0,0,0,0;
.16796,343772,1337684,1445208,451948,33148,244,0,0,0,0;
.58786,1744314,10003422,16974314,9459090,1614906,61806,162,0,0,0,0;
.208012,8780912,71692452,180308420,161380816,51436848,5090124,103932,84,0,0,0,0;
....
where the g.f. of row n is (1-x)^n*[g.f. of column n of A158825];
g.f. of row n of array A158825 is the n-th iteration of x*C(x):
.1,1,2,5,14,42,132,429,1430,4862,16796,58786,208012,742900,...;
.1,2,6,21,80,322,1348,5814,25674,115566,528528,2449746,...;
.1,3,12,54,260,1310,6824,36478,199094,1105478,6227712,...;
.1,4,20,110,640,3870,24084,153306,993978,6544242,43652340,...;
.1,5,30,195,1330,9380,67844,500619,3755156,28558484,...;
.1,6,42,315,2464,19852,163576,1372196,11682348,100707972,...;
.1,7,56,476,4200,38052,351792,3305484,31478628,303208212,...;
.1,8,72,684,6720,67620,693048,7209036,75915708,807845676,...;
....
ROW-REVERSAL yields triangle A122890:
.1;
.0,1;
.0,0,2;
.0,0,1,5;
.0,0,0,10,14;
.0,0,0,8,70,42;
.0,0,0,4,160,424,132;
.0,0,0,1,250,1978,2382,429;
.0,0,0,0,302,6276,19508,12804,1430; ...
where g.f. of row n = (1-x)^n*[g.f. of column n of A122888];
g.f. of row n of A122888 is the n-th iteration of x+x^2:
.1;
.1,1;
.1,2,2,1;
.1,3,6,9,10,8,4,1;
.1,4,12,30,64,118,188,258,302,298,244,162,84,32,8,1; ...
		

Crossrefs

Cf. A158825, A122890 (row-reversal), A122888, columns: A000108, A122892.

Programs

  • Mathematica
    nmax = 11;
    f[0][x_] := x; f[n_][x_] := f[n][x] = f[n - 1][x + x^2] // Expand;
    T = Table[SeriesCoefficient[f[n][x], {x, 0, k}], {n, 0, nmax}, {k, 1, nmax}];
    row[n_] := CoefficientList[(1-x)^n*(T[[All, n]].x^Range[0, nmax])+O[x]^nmax, x] // Reverse;
    Table[row[n], {n, 1, nmax}] // Flatten (* Jean-François Alcover, Oct 26 2018 *)
  • PARI
    {T(n, k)=local(F=x, CAT=serreverse(x-x^2+x*O(x^(n+2))), M, N, P); M=matrix(n+2, n+2, r, c, F=x; for(i=1, r, F=subst(F, x, CAT)); polcoeff(F, c)); Vec(truncate(Ser(vector(n+1,r,M[r,n+1])))*(1-x)^(n+1) +x*O(x^k))[k+1]}

Formula

Row sums equal the factorial numbers.
G.f. of row n = (1-x)^n*[g.f. of column n of A158825] where the g.f. of row n of array A158825 is the n-th iteration of x*C(x) and C(x) is the g.f. of the Catalan sequence A000108.
Row-reversal is triangle A122890 where g.f. of row n of A122890 = (1-x)^n*[g.f. of column n of A122888], and the g.f. of row n of array A122888 is the n-th iteration of x+x^2.

Extensions

Edited by N. J. A. Sloane, Oct 04 2010, to make entries, offset, b-file and link to b-file all consistent.

A166905 Triangle, read by rows, that transforms rows into diagonals in the table A158825 of coefficients in successive iterations of x*Catalan(x) (cf. A000108).

Original entry on oeis.org

1, 1, 1, 6, 4, 1, 54, 33, 9, 1, 640, 380, 108, 16, 1, 9380, 5510, 1610, 270, 25, 1, 163576, 95732, 28560, 5148, 570, 36, 1, 3305484, 1933288, 586320, 110929, 13650, 1071, 49, 1, 75915708, 44437080, 13658904, 2677008, 353600, 31624, 1848, 64, 1, 1952409954
Offset: 0

Views

Author

Paul D. Hanna, Nov 28 2009

Keywords

Examples

			Triangle begins:
1;
1,1;
6,4,1;
54,33,9,1;
640,380,108,16,1;
9380,5510,1610,270,25,1;
163576,95732,28560,5148,570,36,1;
3305484,1933288,586320,110929,13650,1071,49,1;
75915708,44437080,13658904,2677008,353600,31624,1848,64,1;
1952409954,1144564278,355787568,71648322,9962949,973845,66150,2988,81,1;
55573310936,32638644236,10243342296,2107966432,304857190,31795560,2395120,127720,4590,100,1;
...
Coefficients in iterations of x*Catalan(x) form table A158825:
1,1,2,5,14,42,132,429,1430,4862,16796,58786,208012,742900,...;
1,2,6,21,80,322,1348,5814,25674,115566,528528,2449746,...;
1,3,12,54,260,1310,6824,36478,199094,1105478,6227712,...;
1,4,20,110,640,3870,24084,153306,993978,6544242,43652340,...;
1,5,30,195,1330,9380,67844,500619,3755156,28558484,...;
1,6,42,315,2464,19852,163576,1372196,11682348,100707972,...;
1,7,56,476,4200,38052,351792,3305484,31478628,303208212,...;
...
This triangle T transforms rows into diagonals of A158825;
the initial diagonals begin:
A158831: [1,1,6,54,640,9380,163576,3305484,...];
A158832: [1,2,12,110,1330,19852,351792,7209036,...];
A158833: [1,3,20,195,2464,38052,693048,14528217,...];
A158834: [1,4,30,315,4200,67620,1273668,27454218,...].
For example:
T * [1,0,0,0,0,0,0,0,0,0,0,0,0, ...] = A158831;
T * [1,1,2,5,14,42,132,429,1430,...] = A158832;
T * [1,2,6,21,80,322,1348,5814, ...] = A158833;
T * [1,3,12,54,260, 1310, 6824, ...] = A158834.
		

Crossrefs

Programs

  • PARI
    {T(n, k)=local(F=x, G=serreverse(x-x^2+O(x^(n+3))), M, N, P, m=n); M=matrix(m+2, m+2, r, c, F=x;for(i=1, r+c-2, F=subst(F, x, G+x*O(x^(m+2)))); polcoeff(F, c)); N=matrix(m+1, m+1, r, c, F=x;for(i=1, r, F=subst(F, x, G+x*O(x^(m+2)))); polcoeff(F, c)); P=matrix(m+1, m+1, r, c, M[r+1, c]); (P~*N~^-1)[n+1, k+1]}

A122890 Triangle, read by rows, where the g.f. of row n divided by (1-x)^n yields the g.f. of column n in the triangle A122888, for n>=1.

Original entry on oeis.org

1, 0, 1, 0, 0, 2, 0, 0, 1, 5, 0, 0, 0, 10, 14, 0, 0, 0, 8, 70, 42, 0, 0, 0, 4, 160, 424, 132, 0, 0, 0, 1, 250, 1978, 2382, 429, 0, 0, 0, 0, 302, 6276, 19508, 12804, 1430, 0, 0, 0, 0, 298, 15674, 106492, 168608, 66946, 4862, 0, 0, 0, 0, 244, 33148, 451948, 1445208, 1337684, 343772, 16796
Offset: 0

Views

Author

Paul D. Hanna, Sep 18 2006

Keywords

Comments

Main diagonal forms the Catalan numbers (A000108). Row sums gives the factorials. In table A122888, row n lists the coefficients of x^k, k = 1..2^n, in the n-th self-composition of (x + x^2) for n >= 0.
Parker gave the following combinatorial interpretation of the numbers: For n > 0, T(n, j) is the number of sequences c_1c_2...c_n of positive integers such that 1 <= c_i <= i for each i in {1, 2, .., n} with exactly j - 1 values of i such that c_i <= c_{i+1}. - Peter Luschny, May 05 2013

Examples

			Triangle begins:
1;
0,1;
0,0,2;
0,0,1,5;
0,0,0,10,14;
0,0,0,8,70,42;
0,0,0,4,160,424,132;
0,0,0,1,250,1978,2382,429;
0,0,0,0,302,6276,19508,12804,1430;
0,0,0,0,298,15674,106492,168608,66946,4862;
0,0,0,0,244,33148,451948,1445208,1337684,343772,16796;
0,0,0,0,162,61806,1614906,9459090,16974314,10003422,1744314,58786;
0,0,0,0,84,103932,5090124,51436848,161380816,180308420,71692452,8780912,208012; ...
Table A122888 starts:
1;
1, 1;
1, 2, 2, 1;
1, 3, 6, 9, 10, 8, 4, 1;
1, 4, 12, 30, 64, 118, 188, 258, 302, 298, 244, 162, 84, 32, 8, 1;
1, 5, 20, 70, 220, 630, 1656, 4014, 8994, 18654, 35832, 63750,...;
1, 6, 30, 135, 560, 2170, 7916, 27326, 89582, 279622, 832680,...;
where row n gives the g.f. of the n-th self-composition of (x+x^2).
From _Paul D. Hanna_, Apr 11 2009: (Start)
ROW-REVERSAL yields triangle A158830:
1;
1, 0;
2, 0, 0;
5, 1, 0, 0;
14, 10, 0, 0, 0;
42, 70, 8, 0, 0, 0;
132, 424, 160, 4, 0, 0, 0;
429, 2382, 1978, 250, 1, 0, 0, 0; ...
where
g.f. of row n of A158830 = (1-x)^n*[g.f. of column n of A158825];
g.f. of row n of A158825 = n-th iteration of x*Catalan(x).
RELATED ARRAY A158825 begins:
1,1,2,5,14,42,132,429,1430,4862,16796,58786,...;
1,2,6,21,80,322,1348,5814,25674,115566,528528,...;
1,3,12,54,260,1310,6824,36478,199094,1105478,...;
1,4,20,110,640,3870,24084,153306,993978,...;
1,5,30,195,1330,9380,67844,500619,3755156,...;
1,6,42,315,2464,19852,163576,1372196,11682348,...;
1,7,56,476,4200,38052,351792,3305484,31478628,...;
1,8,72,684,6720,67620,693048,7209036,75915708,...; ...
which consists of successive iterations of x*Catalan(x).
(End)
		

Crossrefs

Cf. A122888; A122891 (column sums); diagonals: A122892, A000108.
Cf. related tables: A158830, A158825. [Paul D. Hanna, Apr 11 2009]

Programs

  • Mathematica
    nmax = 11;
    f[0][x_] := x; f[n_][x_] := f[n][x] = f[n - 1][x + x^2] // Expand; T = Table[ SeriesCoefficient[f[n][x], {x, 0, k}], {n, 0, nmax}, {k, 1, nmax}];
    row[n_] := CoefficientList[(1-x)^n*(T[[All, n]].x^Range[0, nmax])+O[x]^nmax, x];
    Table[row[n], {n, 1, nmax}] // Flatten (* Jean-François Alcover, Jul 13 2018 *)

Formula

From Paul D. Hanna, Apr 11 2009: (Start)
G.f. of row n: (1-x)^n*[g.f. of column n of A122888] where the g.f. of row n of A122888 is the n-th iteration of x+x^2.
Row-reversal forms triangle A158830 where g.f. of row n of A158830 = (1-x)^n*[g.f. of column n of A158825], and the g.f. of row n of array A158825 is the n-th iteration of x*C(x) and C(x) is the g.f. of the Catalan sequence A000108. (End)

A158826 Third iteration of x*C(x) where C(x) is the Catalan function (A000108).

Original entry on oeis.org

1, 3, 12, 54, 260, 1310, 6824, 36478, 199094, 1105478, 6227712, 35520498, 204773400, 1191572004, 6990859416, 41313818217, 245735825082, 1470125583756, 8840948601024, 53417237877396, 324123222435804, 1974317194619712
Offset: 1

Views

Author

Paul D. Hanna, Mar 28 2009

Keywords

Comments

Series reversion of x - 3*x^2 + 6*x^3 - 9*x^4 + 10*x^5 - 8*x^6 + 4*x^7 - x^8. - Benedict W. J. Irwin, Oct 19 2016
Column 1 of A106566^3 (see Barry, Section 3). - Peter Bala, Apr 11 2017

Crossrefs

Cf. A121988 (2nd), A158825, A158827 (4th), A158828, A158829.

Programs

  • Mathematica
    max = 22; c[x_] := Sum[ CatalanNumber[n]*x^n, {n, 0, max}]; f[x_] := x*c[x]; CoefficientList[ Series[ f@f@f@x, {x, 0, max}], x] // Rest (* Jean-François Alcover, Jan 24 2013 *)
    Rest@CoefficientList[InverseSeries[x-3x^2+6x^3-9x^4+10x^5-8x^6+4x^7-x^8+O[x]^30], x] (* Benedict W. J. Irwin, Oct 19 2016 *)
  • Maxima
    a(n):=sum(binomial(2*k-2,k-1)*sum(binomial(-k+2*i-1,i-1)*binomial(2*n-i-1,n-1),i,k,n),k,1,n)/n; /* Vladimir Kruchinin, Jan 24 2013 */
    
  • PARI
    a(n)=local(F=serreverse(x-x^2+O(x^(n+1))),G=x); for(i=1,3,G=subst(F,x,G)); polcoeff(G,n)
    
  • Python
    from sympy import binomial as C
    def a(n):
        return sum(C(2*k - 2, k - 1) * sum(C(-k + 2*i - 1, i - 1) * C(2*n - i - 1, n - 1) for i in range(k, n + 1)) for k in range(1, n + 1)) / n
    [a(n) for n in range(1, 51)] # Indranil Ghosh, Apr 12 2017

Formula

a(n) = (1/n)*Sum_{k=1..n} [ binomial(2*k-2,k-1)*Sum_{i=k..n}( binomial(-k+2*i-1,i-1)*binomial(2*n-i-1,n-1) ) ]. - Vladimir Kruchinin, Jan 24 2013
G.f.: (1 - sqrt(-1 + 2*sqrt(-1 + 2*sqrt(1 - 4*x))))/2. - Benedict W. J. Irwin, Oct 19 2016
a(n) ~ 2^(8*n - 3) / (sqrt(5*Pi) * n^(3/2) * 39^(n - 1/2)). - Vaclav Kotesovec, Jul 20 2019
Conjecture D-finite with recurrence 1053*n*(n-1)*(n-2)*(n-3)*a(n) -36*(n-1)*(n-2)*(n-3)*(634*n-1367)*a(n-1) +24*(n-2)*(n-3)*(7966*n^2-43500*n+61181)*a(n-2) -8*(n-3)*(96128*n^3-957424*n^2+3221878*n-3665189)*a(n-3) +16*(91904*n^4-1446528*n^3+8575792*n^2-22703688*n+22652013)*a(n-4) -256*(8*n-35)*(8*n-41)*(8*n-39)*(8*n-37)*a(n-5)=0. - R. J. Mathar, Aug 30 2021
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