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 31-36 of 36 results.

A245260 Decimal expansion of the root of the equation r*log(r/(1-r))=1.

Original entry on oeis.org

7, 8, 2, 1, 8, 8, 2, 9, 4, 2, 8, 0, 1, 9, 9, 9, 0, 1, 2, 2, 0, 2, 9, 7, 0, 7, 5, 9, 2, 6, 7, 4, 4, 7, 8, 0, 1, 8, 1, 9, 0, 8, 4, 0, 3, 9, 6, 6, 2, 9, 9, 5, 1, 6, 8, 7, 0, 9, 6, 8, 3, 3, 2, 3, 9, 5, 6, 9, 1, 6, 9, 9, 4, 1, 2, 4, 6, 7, 4, 6, 7, 1, 9, 5, 3, 8, 2, 3, 9, 2, 9, 0, 6, 6, 7, 3, 2, 5, 1, 3, 6, 6, 7, 5, 8, 5
Offset: 0

Views

Author

Vaclav Kotesovec, Jul 15 2014

Keywords

Examples

			0.78218829428019990122029707592674478018190840396629951687...
		

Crossrefs

Programs

  • Maple
    evalf(solve(r*log(r/(1-r))=1), 100)
  • Mathematica
    RealDigits[r/.FindRoot[r*Log[r/(1-r)]==1, {r, 3/4}, WorkingPrecision->250], 10, 200][[1]]
    RealDigits[1/(1+LambertW[E^(-1)]), 10, 200][[1]]

Formula

Equals 1/(1+LambertW(exp(-1))).

A349706 Square array T(n,k) = Sum_{j=0..k} binomial(k,j) * j^n for n and k >= 0, read by ascending antidiagonals.

Original entry on oeis.org

1, 0, 2, 0, 1, 4, 0, 1, 4, 8, 0, 1, 6, 12, 16, 0, 1, 10, 24, 32, 32, 0, 1, 18, 54, 80, 80, 64, 0, 1, 34, 132, 224, 240, 192, 128, 0, 1, 66, 342, 680, 800, 672, 448, 256, 0, 1, 130, 924, 2192, 2880, 2592, 1792, 1024, 512, 0, 1, 258, 2574, 7400, 11000, 10752, 7840, 4608, 2304, 1024
Offset: 0

Views

Author

Michel Marcus, Nov 26 2021

Keywords

Examples

			Square array begins:
  1 2  4   8   16    32
  0 1  4  12   32    80
  0 1  6  24   80   240
  0 1 10  54  224   800
  0 1 18 132  680  2880
  0 1 34 342 2192 11000
		

Crossrefs

Main diagonal gives A072034.
Cf. A209849.

Programs

  • Mathematica
    T[n_, k_] := Sum[Binomial[k, j] * If[j == n == 0, 1, j^n], {j, 0, k}]; Table[T[n - k, k], {n, 0, 10}, {k, 0, n}] // Flatten (* Amiram Eldar, Nov 26 2021 *)
  • PARI
    T(n,k) = sum(j=0, k, binomial(k,j)*j^n);

A362604 Expansion of e.g.f. 1/(1 + LambertW(-x * exp(x^2))).

Original entry on oeis.org

1, 1, 4, 33, 352, 4805, 80256, 1582693, 36001792, 927974601, 26729943040, 850921057481, 29666297020416, 1124166449205709, 46005243970846720, 2022121401647311245, 95008417631810093056, 4751844218849365365137, 252063937292253895065600
Offset: 0

Views

Author

Seiichi Manyama, Apr 30 2023

Keywords

Crossrefs

Programs

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

Formula

a(n) = n! * Sum_{k=0..floor(n/2)} (n-2*k)^(n-k) / (k! * (n-2*k)!).

A362701 Expansion of e.g.f. 1/(1 + LambertW(-x * exp(x^3/6))).

Original entry on oeis.org

1, 1, 4, 27, 260, 3205, 48276, 859453, 17656696, 411139233, 10700380520, 307819026031, 9698757574716, 332170854765373, 12286858280098780, 488160559069250985, 20732661511284180656, 937357753835195873857, 44948438093966732331984
Offset: 0

Views

Author

Seiichi Manyama, Apr 30 2023

Keywords

Crossrefs

Programs

  • PARI
    my(N=20, x='x+O('x^N)); Vec(serlaplace(1/(1+lambertw(-x*exp(x^3/6)))))

Formula

a(n) = n! * Sum_{k=0..floor(n/3)} (n-3*k)^(n-2*k) / (6^k * k! * (n-3*k)!).

A362704 Expansion of e.g.f. 1/(1 + LambertW(-x^2/2 * exp(x))).

Original entry on oeis.org

1, 0, 1, 3, 18, 130, 1140, 11886, 142408, 1934640, 29357100, 492249340, 9038206056, 180352513848, 3886286296984, 89937276717120, 2224716791224320, 58577968147130176, 1635780290409117648, 48286974141713673072, 1502385897082471446880
Offset: 0

Views

Author

Seiichi Manyama, Apr 30 2023

Keywords

Crossrefs

Programs

  • PARI
    my(N=30, x='x+O('x^N)); Vec(serlaplace(1/(1+lambertw(-x^2/2*exp(x)))))

Formula

a(n) = n! * Sum_{k=0..floor(n/2)} k^(n-k) / (2^k * k! * (n-2*k)!).

A366151 a(n) = T(n, 3), where T(n, k) = Sum_{i=0..n} i^k * binomial(n, i) * (1/2)^(n-k).

Original entry on oeis.org

0, 4, 20, 54, 112, 200, 324, 490, 704, 972, 1300, 1694, 2160, 2704, 3332, 4050, 4864, 5780, 6804, 7942, 9200, 10584, 12100, 13754, 15552, 17500, 19604, 21870, 24304, 26912, 29700, 32674, 35840, 39204, 42772, 46550
Offset: 0

Views

Author

Peter Luschny, Oct 27 2023

Keywords

Comments

A mean of binomials as might occur as the Expectation of random variables.

Crossrefs

T(n, 0) = A000012; T(n, 1) = A001477; T(n, 2) = A002378; T(n, 3) = this sequence.
T(1, n) = A011782; T(2, n) = A063376(n) (with offset 0); T(n, n) = A072034(n).

Programs

  • Maple
    a := n -> n^2*(n + 3): seq(a(n), n = 0..35);

Formula

a(n) = n^2*(n + 3).
a(n) = [x^n] (2*x*(2 + 2*x - x^2))/(x - 1)^4.
a(n) = n! * [x^n] exp(x)*(x^3 + 6*x^2 + 4*x).
Previous Showing 31-36 of 36 results.