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 1-7 of 7 results.

A319509 a(n) = n! * [x^n] 1/(1 - n + exp(x)*(exp(n*x) - 1)/(exp(x) - 1)).

Original entry on oeis.org

1, -1, 13, -828, 145046, -53306325, 35351663831, -38335940184976, 63385171527442332, -151639317344211911505, 503956292395339783686325, -2252032996384696958326480356, 13175456854397460097168816336930, -98695402553214372025148083384255381
Offset: 0

Views

Author

Ilya Gutkovskiy, Sep 21 2018

Keywords

Crossrefs

Cf. A319508.

Programs

  • Mathematica
    Table[n! SeriesCoefficient[1/(1 - n + Exp[x] (Exp[n x] - 1)/(Exp[x] - 1)), {x, 0, n}], {n, 0, 13}]
  • PARI
    default(seriesprecision, 101); {a(n) = n!*polcoeff((1/(1-n+exp(x)*(exp(n*x)-1)/(exp(x)-1)) + O(x^(n+1))), n)};
    for(n=0, 25, print1(a(n), ", ")) \\ G. C. Greubel, Oct 09 2018

Formula

a(n) = n! * [x^n] 1/(1 - n + exp(x) + exp(2*x) + exp(3*x) + ... + exp(n*x)).

A320253 Square array A(n,k), n>=0, k>=0, read by antidiagonals, where column k is the expansion of e.g.f. 1/(1 + k - Sum_{j=1..k} exp(j*x)).

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 3, 3, 0, 1, 6, 23, 13, 0, 1, 10, 86, 261, 75, 0, 1, 15, 230, 1836, 3947, 541, 0, 1, 21, 505, 7900, 52250, 74613, 4683, 0, 1, 28, 973, 25425, 361754, 1858716, 1692563, 47293, 0, 1, 36, 1708, 67473, 1706629, 20706700, 79345346, 44794221, 545835, 0
Offset: 0

Views

Author

Ilya Gutkovskiy, Oct 08 2018

Keywords

Examples

			E.g.f. of column k: A_k(x) = 1 + (1/2)*k*(k + 1)*x/1! + (1/6)*k*(3*k^3 + 8*k^2 + 6*k + 1)*x^2/2! + (1/4)*k^2*(k + 1)^2*(3*k^2 + 7*k + 3)*x^3/3! + (1/30)*k*(45*k^7 + 270*k^6 + 635*k^5 + 741*k^4 + 440*k^3 + 115*k^2 + 5*k - 1)*x^4/4! + ...
Square array begins:
  1,    1,      1,        1,         1,          1,  ...
  0,    1,      3,        6,        10,         15,  ...
  0,    3,     23,       86,       230,        505,  ...
  0,   13,    261,     1836,      7900,      25425,  ...
  0,   75,   3947,    52250,    361754,    1706629,  ...
  0,  541,  74613,  1858716,  20706700,  143195025,  ...
		

Crossrefs

Main diagonal gives A319508.

Programs

  • Mathematica
    Table[Function[k, n! SeriesCoefficient[1/(1 + k - Sum[Exp[i x], {i, 1, k}]), {x, 0, n}]][j - n], {j, 0, 9}, {n, 0, j}] // Flatten
    Table[Function[k, n! SeriesCoefficient[1/(1 + k - Exp[x] (Exp[k x] - 1)/(Exp[x] - 1)), {x, 0, n}]][j - n], {j, 0, 9}, {n, 0, j}] // Flatten

Formula

E.g.f. of column k: 1/(1 + k - exp(x)*(exp(k*x) - 1)/(exp(x) - 1)).

A320288 a(n) = n! * [x^n] exp(exp(x)*(exp(n*x) - 1)/(exp(x) - 1) - n).

Original entry on oeis.org

1, 1, 14, 504, 35054, 4004100, 680823583, 161337142848, 50830272555828, 20549783554154775, 10370522690234157175, 6390016526512315766520, 4721172172018812127424546, 4119920939845363203406535407, 4192465334819134111336349480680, 4920767556196547768620408273728000
Offset: 0

Views

Author

Ilya Gutkovskiy, Oct 09 2018

Keywords

Crossrefs

Programs

  • Mathematica
    Table[n! SeriesCoefficient[Exp[Exp[x] (Exp[n x] - 1)/(Exp[x] - 1) - n], {x, 0, n}], {n, 0, 15}]
  • PARI
    a(n)={my(A=O(x^(n+2))); n!*polcoef((exp(exp(x + A)*(exp(n*x + A) - 1)/(exp(x + A) - 1) - n)), n)}; \\ Andrew Howroyd, Nov 04 2018

Formula

a(n) = n! * [x^n] exp(exp(x) + exp(2*x) + exp(3*x) + ... + exp(n*x) - n).
a(n) ~ c * exp(n*exp(1) - 3*n) * n^(2*n), where c = exp((exp(1) - 1)/2) / sqrt(exp(1) - 1) = 1.801245710492990660565773944914841332489711300610532... - Vaclav Kotesovec, Jul 02 2022, updated Mar 18 2024

A331340 a(n) = n! * [x^n] 1 / (1 + Sum_{k=1..n} log(1 - k*x)).

Original entry on oeis.org

1, 1, 23, 1872, 371524, 147316050, 102823452318, 115685840003328, 196669439127051840, 480847207762313690400, 1626231663646322798946000, 7372321556702072183715972096, 43653032698484678876818157764224, 330351436922959495109028135649934640
Offset: 0

Views

Author

Ilya Gutkovskiy, Jan 14 2020

Keywords

Crossrefs

Programs

  • Mathematica
    Table[n! SeriesCoefficient[1/(1 + Sum[Log[1 - k x], {k, 1, n}]), {x, 0, n}], {n, 0, 13}]
    Table[n! SeriesCoefficient[1/(1 + Log[Sum[StirlingS1[n + 1, n - k + 1] x^k, {k, 0, n}]]), {x, 0, n}], {n, 0, 13}]

Formula

a(n) = n! * [x^n] 1 / (1 + log(Sum_{k=0..n} Stirling1(n+1,n-k+1) * x^k)).
a(n) ~ sqrt(Pi) * n^(3*n + 1/2) / (2^(n - 1/2) * exp(n - 5/3)). - Vaclav Kotesovec, Jan 28 2020

A331341 a(n) = n! * [x^n] 1 / (1 - Sum_{k=1..n} log(1 + k*x)).

Original entry on oeis.org

1, 1, 13, 864, 151276, 55463850, 36662614458, 39635566403328, 65354864056231104, 155978053040893370400, 517297066212058929642000, 2307448887344816064221408256, 13478142770116878179295616074624, 100820731073923375628659569173854704
Offset: 0

Views

Author

Ilya Gutkovskiy, Jan 14 2020

Keywords

Crossrefs

Programs

  • Mathematica
    Table[n! SeriesCoefficient[1/(1 - Sum[Log[1 + k x], {k, 1, n}]), {x, 0, n}], {n, 0, 13}]
    Table[n! SeriesCoefficient[1/(1 - Log[Sum[Abs[StirlingS1[n + 1, n - k + 1]] x^k, {k, 0, n}]]), {x, 0, n}], {n, 0, 13}]

Formula

a(n) = n! * [x^n] 1 / (1 - log(Sum_{k=0..n} |Stirling1(n+1,n-k+1)| * x^k)).
a(n) ~ sqrt(Pi) * n^(3*n + 1/2) / (2^(n - 1/2) * exp(n - 1/3)). - Vaclav Kotesovec, Jan 28 2020

A355428 a(n) = n! * [x^n] 1/(1 - Sum_{k=1..n} (exp(k*x) - 1)/k).

Original entry on oeis.org

1, 1, 11, 284, 13564, 1037479, 116171621, 17916010524, 3640962169776, 942959405612913, 303168464105203113, 118474395231479349050, 55306932183983923942940, 30397993745996492901617435, 19429788681469866219869997285
Offset: 0

Views

Author

Seiichi Manyama, Jul 01 2022

Keywords

Crossrefs

Main diagonal of A355427.
Cf. A319508.

Programs

  • Mathematica
    Table[n! * SeriesCoefficient[1/(1 + HarmonicNumber[n] + E^((n + 1)*x) * LerchPhi[E^x, 1, n + 1] + Log[1 - E^x]), {x, 0, n}], {n, 0, 20}] (* Vaclav Kotesovec, Jul 02 2022 *)
  • PARI
    a(n) = n!*polcoef(1/(1-sum(k=1, n, (exp(k*x+x*O(x^n))-1)/k)), n);

Formula

a(n) ~ c * d^n * n^(2*n + 1/2), where d = 0.4573611067742364103005235654624761643997061199669064548746966610712579358... and c = 2.41592773370058066984975000807924527905758896927935098069320182397... - Vaclav Kotesovec, Jul 02 2022

A331582 a(n) = n! * [x^n] exp(n - exp(x) * (exp(n*x) - 1) / (exp(x) - 1)).

Original entry on oeis.org

1, -1, 4, 0, -1654, 102750, -4079389, -178722208, 83191059372, -14561829897345, 1115121827539325, 403631463559529040, -251989999508801085674, 76158421344845152140737, -3994730250899559184766830, -13162858116922635098226480000, 10823217968258750568539067678392
Offset: 0

Views

Author

Ilya Gutkovskiy, Jan 21 2020

Keywords

Crossrefs

Programs

  • Mathematica
    Table[n! SeriesCoefficient[Exp[n - Exp[x] (Exp[n x] - 1)/(Exp[x] - 1)], {x, 0, n}], {n, 0, 16}]
    b[n_, k_] := b[n, k] = If[n == 0, 1, -Sum[Binomial[n - 1, j - 1] Sum[i^j, {i, 1, k}] b[n - j, k], {j, 1, n}]]; a[n_] := b[n, n]; Table[a[n], {n, 0, 16}]

Formula

a(n) = n! * [x^n] exp(n - exp(x) - exp(2*x) - exp(3*x) - ... - exp(n*x)).
Showing 1-7 of 7 results.