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 1-10 of 17 results. Next

A286786 Column 1 of A286781.

Original entry on oeis.org

1, 9, 91, 1063, 14193, 213953, 3602891, 67168527, 1375636129, 30741614905, 745133551611, 19485223248311, 547092691302545, 16422216867929457, 524970306508659691, 17809453107819266335, 639153386976421052481, 24196474723945543441769, 963736849031626750711451, 40289411871795861783689799
Offset: 1

Views

Author

Gheorghe Coserea, May 16 2017

Keywords

Crossrefs

Cf. A286781.

Programs

  • PARI
    A286781_ser(N, t='t) = {
      my(x='x+O('x^N), y0=1+O('x^N), y1=0, n=1);
      while(n++,
        y1 = (1 + x*y0 + 2*x^2*y0')*(1 - x*y0*(1-t))/(1-x*y0)^2;
        if (y1 == y0, break()); y0 = y1;);
      y0;
    };
    Kol(K,N=20) = {
      my(s = A286781_ser(N+K, 't+O('t^(K+1))));
      vector(N, n, polcoeff(polcoeff(s, K+n-1), K));
    };
    Kol(1)

A286787 Column 2 of A286781.

Original entry on oeis.org

1, 23, 416, 7344, 134613, 2620379, 54636792, 1223392968, 29409134545, 757686550455, 20870680635528, 612964613117960, 19140704352872949, 633710701752022635, 22185391759982205904, 819180275431111135536, 31826528430233802890049, 1298154677953792936043447, 55473817874169725876166480
Offset: 2

Views

Author

Gheorghe Coserea, May 16 2017

Keywords

Crossrefs

Cf. A286781.

Programs

  • PARI
    A286781_ser(N, t='t) = {
      my(x='x+O('x^N), y0=1+O('x^N), y1=0, n=1);
      while(n++,
        y1 = (1 + x*y0 + 2*x^2*y0')*(1 - x*y0*(1-t))/(1-x*y0)^2;
        if (y1 == y0, break()); y0 = y1;);
      y0;
    };
    Kol(K,N=20) = {
      my(s = A286781_ser(N+K, 't+O('t^(K+1))));
      vector(N, n, polcoeff(polcoeff(s, K+n-1), K));
    };
    Kol(2)

A286788 Column 3 of A286781.

Original entry on oeis.org

1, 46, 1350, 34362, 842751, 20862684, 533394516, 14251251012, 400275122533, 11849888387786, 370032953752618, 12183464636804638, 422529226131247475, 15413172354966378040, 590459747844232859976, 23715530712277152761928, 997006212536288359365609, 43800374567467950834916070
Offset: 3

Views

Author

Gheorghe Coserea, May 16 2017

Keywords

Crossrefs

A286789 Column 4 of A286781.

Original entry on oeis.org

1, 80, 3550, 125195, 4009832, 124266346, 3854188670, 121943460540, 3979525634005, 134806148044750, 4756728585598416, 175132764223880035, 6731931366383154760, 270129431174068396380, 11308903054417009540644, 493544598057755406560688, 22431785171561428611320865
Offset: 4

Views

Author

Gheorghe Coserea, May 16 2017

Keywords

Crossrefs

A286790 Column 5 of A286781.

Original entry on oeis.org

1, 127, 8085, 382358, 15653598, 598415692, 22280470762, 828351390146, 31225895068199, 1204894853397543, 47870402081423775, 1965205314867907972, 83531844407610101388, 3679988322044604002256, 168093873703636990132596, 7960504783782783371445468
Offset: 5

Views

Author

Gheorghe Coserea, May 16 2017

Keywords

Crossrefs

A286791 Column 6 of A286781.

Original entry on oeis.org

1, 189, 16576, 1023340, 52563182, 2445890678, 108248782988, 4693939818672, 203214066766123, 8891156436472127, 396276632116578640, 18084968846773765272, 847923332620865268252, 40927316768759272656876, 2036183873275911481501656, 104482592642320957223810448
Offset: 6

Views

Author

Gheorghe Coserea, May 16 2017

Keywords

Crossrefs

A286792 Column 7 of A286781.

Original entry on oeis.org

1, 268, 31356, 2471008, 156688950, 8769288752, 457164358716, 22959079494036, 1135195898868631, 56066461542293032, 2793059847097230456, 141275485011659499936, 7287917154352619470284, 384587934464798917826784, 20802129691800205763744280, 1154767942465769017202459544
Offset: 7

Views

Author

Gheorghe Coserea, May 16 2017

Keywords

Crossrefs

A286793 Column 8 of A286781.

Original entry on oeis.org

1, 366, 55650, 5493004, 423998498, 28236562692, 1719625254528, 99364697625603, 5581585635090040, 309848573192308938, 17191725056094651066, 960908576231662848594, 54403314773991195041214, 3132006013784614723699158, 183841318769012678798846646, 11022935912713058281592718756
Offset: 8

Views

Author

Gheorghe Coserea, May 16 2017

Keywords

Crossrefs

A286794 Row sums of A286781.

Original entry on oeis.org

1, 3, 20, 189, 2232, 31130, 497016, 8907885, 176829104, 3849436062, 91187523000, 2335691914050, 64344487654800, 1897619527612692, 59667237154623280, 1993022006345620605, 70488571028815935072, 2631925423768158446390, 103469607286411235941944, 4272438866376100717458486
Offset: 0

Views

Author

Gheorghe Coserea, May 16 2017

Keywords

Examples

			A(x) = 1 + 3*x + 20*x^2 + 189*x^3 + 2232*x^4 + 31130*x^5 + ...
		

Crossrefs

Programs

  • Mathematica
    max = 22; (* B(x) is A000699(x) *) B[_] = 0;
    Do[B[x_] = x + x^2 D[B[x]^2/x, x] + O[x]^max // Normal, max];
    A[x_] = (1 - x/B[x])/x + O[x]^max;
    Drop[CoefficientList[A[x], x], -2] (* Jean-François Alcover, Oct 25 2018 *)
  • PARI
    A286781_ser(N, t='t) = {
      my(x='x+O('x^N), y0=1+O('x^N), y1=0, n=1);
      while(n++,
        y1 = (1 + x*y0 + 2*x^2*y0')*(1 - x*y0*(1-t))/(1-x*y0)^2;
        if (y1 == y0, break()); y0 = y1;);
      y0;
    };
    Vec(A286781_ser(20,1))
    
  • PARI
    A000699_seq(N) = {
      my(a = vector(N)); a[1] = 1;
      for (n=2, N, a[n] = sum(k=1, n-1, (2*k-1)*a[k]*a[n-k])); a;
    };
    A286794_seq(N) = Vec((1-1/Ser(A000699_seq(N+1)))/x);
    A286794_seq(20)

Formula

a(n) = Sum_{k=0..n} A286781(n,k).
A(x) = (1-x/A000699(x))/x, A208975(x) = 1 + x*A(-x).
a(n) ~ 4*exp(-1)/sqrt(Pi) * n^(3/2) * 2^n * n! * (1 - 3/(8*n) - 215/(128*n^2) + O(1/n^3)). (see Borinsky link) - Gheorghe Coserea, Oct 23 2017

A286782 Triangle T(n,k) read by rows: coefficients of polynomials P_n(t) defined in Formula section.

Original entry on oeis.org

1, 1, 6, 3, 50, 45, 5, 518, 637, 161, 7, 6354, 9567, 3744, 414, 9, 89782, 156123, 80784, 14850, 880, 11, 1435330, 2781389, 1749969, 446706, 46150, 1651, 13, 25625910, 54043365, 39305685, 12641265, 1877925, 121275, 2835, 15, 505785122, 1141864959, 928825464, 354665628, 68167144, 6500086, 281792, 4556, 17, 10944711398, 26137086451, 23244466392, 10134495804, 2361060574, 297418362, 19443460, 595764, 6954, 19
Offset: 0

Views

Author

Gheorghe Coserea, May 14 2017

Keywords

Comments

Row n>0 contains n terms.
T(n,k) is the number of Feynman's diagrams with k fermionic loops in the order n of the perturbative expansion in dimension zero for the vertex function in a many-body theory of fermions with two-body interaction (see Molinari link).

Examples

			A(x;t) = 1 + x + (6 + 3*t)*x^2 + (50 + 45*t + 5*t^2)*x^3 + ...
Triangle starts:
n\k  [0]       [1]       [2]       [3]       [4]      [5]     [6]    [7]
[0]  1;
[1]  1;
[2]  6,        3;
[3]  50,       45,       5;
[4]  518,      637,      161,      7;
[5]  6354,     9567,     3744,     414,      9;
[6]  89782,    156123,   80784,    14850,    880,     11;
[7]  1435330,  2781389,  1749969,  446706,   46150,   1651,   13;
[8]  25625910, 54043365, 39305685, 12641265, 1877925, 121275, 2835,  15;
[9]  ...
		

Programs

  • Mathematica
    max = 10; y0[x_, t_] = 1; y1[x_, t_] = 0; For[n = 1, n <= max, n++, y1[x_, t_] = (1 + x*y0[x, t] + 2*x^2*D[y0[x, t], x])*(1 - x*y0[x, t]*(1 - t))/(1 - x*y0[x, t])^2 + O[x]^n // Normal; y0[x_, t_] = y1[x, t]];
    row[n_] := (2n+1) CoefficientList[Coefficient[y0[x, t], x, n], t];
    T[0, 0] = 1; T[n_, k_] := row[n-1][[k+1]];
    Table[T[n, k], {n, 0, max}, {k, 0, If[n == 0, 0, n-1]}] // Flatten (* Jean-François Alcover, May 19 2017, adapted from PARI *)
  • PARI
    A286781_ser(N,t='t) = {
      my(x='x+O('x^N), y0=1+O('x^N), y1=0, n=1);
      while(n++,
        y1 = (1 + x*y0 + 2*x^2*y0')*(1 - x*y0*(1-t))/(1-x*y0)^2;
        if (y1 == y0, break()); y0 = y1;);
      y0;
    };
    A286782_ser(N,t='t) = my(s=A286781_ser(N,t)); 1 + x*s + 2*x^2 * deriv(s,'x);
    concat(apply(p->Vecrev(p), Vec(A286782_ser(10))))

Formula

A(x;t) = Sum_{n>=0} P_n(t)*x^n = 1 + x*s + 2*x^2 * deriv(s,x), where s(x;t) = A286781(x;t) and P_n(t) = Sum_{k=0..n-1} T(n,k)*t^k for n>0.
T(n+1,k) = (2*n+1)*A286781(n,k), A005416(n)=T(n,0), A088218(n)=P_n(-1).
Showing 1-10 of 17 results. Next