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.

Previous Showing 21-26 of 26 results.

A369722 Expansion of e.g.f. exp( (3/2) * (1-sqrt(1-4*x)) ).

Original entry on oeis.org

1, 3, 15, 117, 1305, 19323, 359559, 8084205, 213425361, 6475518675, 222088463199, 8497641269637, 358899729493545, 16585866328129803, 832523413971932055, 45105537151437499197, 2623613865509122341921, 163070009495928522691875
Offset: 0

Views

Author

Seiichi Manyama, Jan 30 2024

Keywords

Crossrefs

Programs

  • PARI
    my(N=20, x='x+O('x^N)); Vec(serlaplace(exp(3/2*(1-sqrt(1-4*x)))))

Formula

a(0) = 1; a(n) = Sum_{k=0..n-1} 3^(n-k) * (n-1+k)! / (k! * (n-1-k)!).
a(n) = 2*(2*n-3)*a(n-1) + 9*a(n-2).

A369723 Expansion of e.g.f. exp( 2 * (1-sqrt(1-4*x)) ).

Original entry on oeis.org

1, 4, 24, 208, 2464, 37824, 720256, 16450816, 439245312, 13440572416, 464007387136, 17847329869824, 757011972726784, 35108108023349248, 1767517592731090944, 96007679735852498944, 5596725706163142393856, 348533116657888468402176
Offset: 0

Views

Author

Seiichi Manyama, Jan 30 2024

Keywords

Crossrefs

Programs

  • PARI
    my(N=20, x='x+O('x^N)); Vec(serlaplace(exp(2*(1-sqrt(1-4*x)))))

Formula

a(0) = 1; a(n) = Sum_{k=0..n-1} 4^(n-k) * (n-1+k)! / (k! * (n-1-k)!).
a(n) = 2*(2*n-3)*a(n-1) + 16*a(n-2).

A369724 Expansion of e.g.f. exp( (5/2) * (1-sqrt(1-4*x)) ).

Original entry on oeis.org

1, 5, 35, 335, 4225, 67525, 1321075, 30751775, 832573025, 25745985125, 896177819875, 34698406783375, 1479737530398625, 68935386567921125, 3483762766656021875, 189846574063623209375, 11098195364856546690625, 692834276972696475053125
Offset: 0

Views

Author

Seiichi Manyama, Jan 30 2024

Keywords

Crossrefs

Programs

  • PARI
    my(N=20, x='x+O('x^N)); Vec(serlaplace(exp(5/2*(1-sqrt(1-4*x)))))

Formula

a(0) = 1; a(n) = Sum_{k=0..n-1} 5^(n-k) * (n-1+k)! / (k! * (n-1-k)!).
a(n) = 2*(2*n-3)*a(n-1) + 25*a(n-2).

A383796 Expansion of g.f.: exp(Sum_{n>=1} A295432(n)*x^n/n).

Original entry on oeis.org

1, 462, 396453, 425295010, 511915968714, 661059663660060, 895093835464198893, 1254056426977089876570, 1802794259810040618367902, 2644298823194748929633091780, 3941742074897786728895080586082, 5954164159064906497558129244865108, 9094122817144126105637193154022530612
Offset: 0

Views

Author

Karol A. Penson, Jun 11 2025

Keywords

Crossrefs

Programs

  • PARI
    seq(n)=Vec(exp(sum(n=1, n, (12*n)!*(3*n)!*(2*n)!*x^n/(n*((6*n)!)^2*(4*n)!*n!), O(x*x^n)))) \\ Andrew Howroyd, Jun 11 2025

Formula

G.f.: exp(Sum_{n>=1} (12*n)!*(3*n)!*(2*n)!*x^n/(n*((6*n)!)^2*(4*n)!*n!)).

A251660 Table of coefficients in functions R(n,x) defined by R(n,x) = exp( n*x*G(n,x)^(n-1) ) / G(n,x)^(n-1) where G(n,x) = 1 + x*G(n,x)^n, for rows n>=1.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 3, 8, 1, 1, 1, 4, 21, 56, 1, 1, 1, 5, 40, 261, 592, 1, 1, 1, 6, 65, 712, 4833, 8512, 1, 1, 1, 7, 96, 1505, 18784, 120303, 155584, 1, 1, 1, 8, 133, 2736, 51505, 663424, 3778029, 3456896, 1, 1, 1, 9, 176, 4501, 115056, 2354725, 29480896, 143531433, 90501632, 1
Offset: 1

Views

Author

Paul D. Hanna, Dec 21 2014

Keywords

Examples

			This table begins:
n=1: [1, 1,  1,   1,     1,       1,        1,           1, ...];
n=2: [1, 1,  2,   8,    56,     592,     8512,      155584, ...];
n=3: [1, 1,  3,  21,   261,    4833,   120303,     3778029, ...];
n=4: [1, 1,  4,  40,   712,   18784,   663424,    29480896, ...];
n=5: [1, 1,  5,  65,  1505,   51505,  2354725,   135258625, ...];
n=6: [1, 1,  6,  96,  2736,  115056,  6455376,   454666176, ...];
n=7: [1, 1,  7, 133,  4501,  224497, 14926387,  1245099709, ...];
n=8: [1, 1,  8, 176,  6896,  397888, 30584128,  2948178304, ...];
n=9: [1, 1,  9, 225, 10017,  656289, 57255849,  6262226721, ...];
n=10:[1, 1, 10, 280, 13960, 1023760, 99935200, 12226859200, ...]; ...
where e.g.f. of row n equals: exp( n*x*G(n,x)^(n-1) ) / G(n,x)^(n-1).
Related table of coefficients in G(n,x) = 1 + x*G(n,x)^n  begins:
n=1: [1, 1,  1,   1,    1,     1,      1,        1, ...];
n=2: [1, 1,  2,   5,   14,    42,    132,      429, ...];
n=3: [1, 1,  3,  12,   55,   273,   1428,     7752, ...];
n=4: [1, 1,  4,  22,  140,   969,   7084,    53820, ...];
n=5: [1, 1,  5,  35,  285,  2530,  23751,   231880, ...];
n=6: [1, 1,  6,  51,  506,  5481,  62832,   749398, ...];
n=7: [1, 1,  7,  70,  819, 10472, 141778 , 1997688, ...];
n=8: [1, 1,  8,  92, 1240, 18278, 285384,  4638348, ...];
n=9: [1, 1,  9, 117, 1785, 29799, 527085,  9706503, ...];
n=10:[1, 1, 10, 145, 2470, 46060, 910252, 18730855, ...]; ...
		

Crossrefs

Programs

  • PARI
    {T(n,k)=local(G=1); for(i=0, k, G=1+x*G^n +x*O(x^k)); k!*polcoeff(exp(n*x*G^(n-1))/G^(n-1), k)}
    /* Print as a rectangular table */
    for(n=1, 10, for(k=0,10, print1(T(n,k), ", "));print(""))
    /* Print as a flattened table */
    for(n=0, 12, for(k=0,n, print1(T(n-k+1,k), ", "));)
    /* Print the Related table of functions G(n,x) = 1 + x*G(n,x)^n */
    {R(n,k)=local(G=1); for(i=0, k, G=1+x*G^n +x*O(x^k)); polcoeff(G, k)}
    for(n=1, 10, for(k=0,10, print1(R(n,k), ", "));print(""))
    
  • PARI
    /* Binomial sum formula for term T(n,k) */
    {T(n,k) = if(k<=1,1,sum(j=0,k, n^j * k!/j! * binomial(n*(k-1)-j, k-j) * (j-1)/(k-1)))}
    for(n=1, 10, for(k=0, 10, print1(T(n, k), ", ")); print(""))

Formula

E.g.f. of row n, R(n,x), for n>=1, satisfies:
(1) [x^k/k!] R(n,x)^(k+1) = n^(k-1) * (n+k) * (k+1)^(k-2) for k>=0.
(2) R(n,x) = exp( n*x*G(n,x)^(n-1) ) / G(n,x)^(n-1), where G(n,x) = 1 + x*G(n,x)^n.
(3) R'(n,x)/R(n,x) = G(n,x)^(n-1), where G(n,x) = 1 + x*G(n,x)^n.
T(n,k) = Sum_{j=0..k} n^j * k!/j! * binomial(n*(k-1)-j, k-j) * (j-1)/(k-1) for k>1, n>=1.

A384957 Expansion of g.f.: exp(Sum_{n>=1} A295433(n)*x^n/n).

Original entry on oeis.org

1, 990, 2206149, 6450139410, 21553605027306, 77957908218716988, 297118041166459732781, 1175248212459867447863562, 4779368947089383238327733950, 19858241947988743766121587718308, 83936671517628352407663509802203682, 359778601391313651280693986124971038388, 1560159110515342136997114532804454280500084
Offset: 0

Views

Author

Karol A. Penson, Jun 13 2025

Keywords

Crossrefs

Programs

  • PARI
    seq(n)=Vec(exp(sum(n=1, n, (12*n)!*n!*x^n/((8*n)!*(3*n)!*(2*n)!)/n, O(x*x^n)) )) \\ Andrew Howroyd, Jun 13 2025

Formula

G.f.: exp(Sum_{n>=1} (12*n)!*n!*x^n/((8*n)!*(3*n)!*(2*n)!)/n).
Previous Showing 21-26 of 26 results.