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 1-2 of 2 results.

A266521 E.g.f.: Log( Sum_{n>=0} (n + y)^(2*n) * x^n/n! ) = Sum_{n>=1} Sum_{k=0..n+1} T(n,k) * x^n*y^k/n!, as a triangle of coefficients T(n,k) read by rows.

Original entry on oeis.org

1, 2, 1, 15, 28, 18, 4, 683, 1278, 933, 316, 42, 62038, 117440, 92680, 38240, 8272, 752, 9342629, 17880090, 14855385, 6881640, 1880340, 288048, 19360, 2100483216, 4054752672, 3490688496, 1743156480, 547098240, 108228192, 12523584, 654912, 658746323647, 1279910119670, 1130161189549, 594323331364, 204256939502, 47125635760, 7147508032, 652959872, 27546736, 274730459045232, 536368375356928, 482514140459520, 263340552849920, 96404466197760, 24628940050176, 4404380994048, 533057051648, 39701769216, 1388207872
Offset: 1

Views

Author

Paul D. Hanna, Jan 01 2016

Keywords

Comments

Row sums form A266520, coefficients in Log( Sum_{n>=0} (n+1)^(2*n) * x^n/n! ).
Column 0 forms A266519, coefficients in log( Sum_{n>=0} n^(2*n) * x^n/n! ).
Rightmost border is A266526.

Examples

			E.g.f.: A(x,y) = x * (1 + 2*y + y^2) +
x^2/2! * (15 + 28*y + 18*y^2 + 4*y^3) +
x^3/3! * (683 + 1278*y + 933*y^2 + 316*y^3 + 42*y^4) +
x^4/4! * (62038 + 117440*y + 92680*y^2 + 38240*y^3 + 8272*y^4 + 752*y^5) +
x^5/5! * (9342629 + 17880090*y + 14855385*y^2 + 6881640*y^3 + 1880340*y^4 + 288048*y^5 + 19360*y^6) +
x^6/6! * (2100483216 + 4054752672*y + 3490688496*y^2 + 1743156480*y^3 + 547098240*y^4 + 108228192*y^5 + 12523584*y^6 + 654912*y^7) +...
where
exp(A(x,y)) = 1 + (1 + y)*x + (2 + y)^4*x^2/2! + (3 + y)^6*x^3/3! + (4 + y)^8*x^4/4! + (5 + y)^10*x^5/5! + (6 + y)^12*x^6/6! +...
This triangle begins:
1, 2, 1;
15, 28, 18, 4;
683, 1278, 933, 316, 42;
62038, 117440, 92680, 38240, 8272, 752;
9342629, 17880090, 14855385, 6881640, 1880340, 288048, 19360;
2100483216, 4054752672, 3490688496, 1743156480, 547098240, 108228192, 12523584, 654912;
658746323647, 1279910119670, 1130161189549, 594323331364, 204256939502, 47125635760, 7147508032, 652959872, 27546736;
274730459045232, 536368375356928, 482514140459520, 263340552849920, 96404466197760, 24628940050176, 4404380994048, 533057051648, 39701769216, 1388207872;
147034646085347145, 288100398039817266, 262835789583073329, 147457696629622032, 56514667400140392, 15510808994500512, 3097157140510272, 445604738641920, 44324678623680, 2758053332736, 81621893376; ...
		

Crossrefs

Programs

  • PARI
    {T(n,k) = n! * polcoeff( polcoeff( log( sum(m=0,n+1, (m + y)^(2*m) *x^m/m! ) +x*O(x^n) ),n,x), k,y)}
    for(n=1,10, for(k=0,n+1, print1(T(n,k),", "));print(""))

A266520 E.g.f.: log( Sum_{n>=0} (n+1)^(2*n) * x^n/n! ).

Original entry on oeis.org

4, 65, 3252, 319422, 51147492, 12057585792, 3922351554132, 1682965461982320, 921043932965502660, 626381920753520549760, 518386843395242486312436, 513135100084662037473481728, 598802670522558079363471420836, 813678320999818358850938259419136, 1273853548265201707125719549854268820, 2276462439285471707026207820594795624448
Offset: 1

Views

Author

Paul D. Hanna, Dec 31 2015

Keywords

Comments

From two partial functions f,g on [n], form a labeled directed graph with vertex set [n] and edge set: {(x -> f(x)):x in [n]} Union {(x -> g(x)):x in [n]}. Then a(n) is the number of such graphs that are weakly connected. - Geoffrey Critzer, Dec 06 2021

Crossrefs

Cf. A266519.

Programs

  • Mathematica
    nn = 10; g[x_] := Sum[(n + 1)^(2 n) x^n/n!, {n, 0, nn}] ;
    Drop[Range[0, nn]! CoefficientList[Series[Log[g[x]], {x, 0, nn}], x], 1] (* Geoffrey Critzer, Dec 06 2021 *)
  • PARI
    {a(n) = n! * polcoeff( log( sum(m=0,n, (m+1)^(2*m) * x^m/m!) +x*O(x^n)), n)}
    for(n=1,20,print1(a(n),", "))
Showing 1-2 of 2 results.