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 1-4 of 4 results.

A121376 Numerator of PolyLog(-n, 1/n).

Original entry on oeis.org

-1, 6, 33, 380, 3535, 189714, 285929, 319735800, 1160703963, 145739620510, 86294277091, 10914811650686580, 60229285882649, 163637596919801624970, 3392462704290802545, 669084376596453009616, 370468452361579892135179, 157145213515550643044429571846
Offset: 1

Views

Author

Alexander Adamchuk, Sep 06 2006

Keywords

Examples

			PolyLog(-n, 1/n) begins -1/12, 6, 33/8, 380/81, 3535/512, 189714/15625, ...
		

Crossrefs

Cf. A121985 (denominator).
Cf. A119758.

Programs

  • Mathematica
    Numerator[Table[PolyLog[ -n,1/n],{n,1,40}]]
  • PARI
    a(n)=if(n==1,-1,numerator(polylog(-n,1/n))) \\ Charles R Greathouse IV, Jul 14 2014

Formula

a(n) = numerator( PolyLog( -n, 1/n ) ). For n>1 a(n) = numerator( (-1)^n * PolyLog( -n, n ) ).
PolyLog(-n, 1/n) = a(n)/A121985(n) = Sum_{k>=1} k^n/n^k, for n > 1. n divides a(n). p^k divides a(p^k) for all prime p and integer k>0. p^k divides a(p^k-1) for prime p>2 and integer k>0. Also PolyLog(n, z) = Sum_{k>=1} z^k/k^n.
For n>1, a(n) is the numerator of n*A122778(n)/(n-1)^(n+1) = Sum_{k=0..n} A(n,k)*n^(k+1)/(n-1)^(n+1). For n>1, a(n) = n * A122778(n)/gcd(A122778(n),(n-1)^(n+1)). - Max Alekseyev, Sep 11 2006

A086914 a(n) = ((n-1)^n/n)*Sum_{k>=1} (k^n/n^k).

Original entry on oeis.org

0, 3, 11, 95, 1414, 31619, 980328, 39966975, 2063473712, 131165658459, 10041515879680, 909567637557215, 96070344004816128, 11688399779985830355, 1621144844290431509504, 254042974238965752088575
Offset: 1

Views

Author

Benoit Cloitre, Sep 24 2003

Keywords

Comments

Appears to always be an integer.

Crossrefs

Programs

  • Mathematica
    Table[Sum[(n-1)^n*k^n/n^(k+1), {k, 1, Infinity}], {n, 1, 20}] (* Vaclav Kotesovec, Oct 16 2016 *)

Formula

a(n) = Euler(n, n)/(n-1) where Euler(n, x) is Eulerian polynomial of degree n (cf. A008292). - Vladeta Jovovic, Sep 26 2003
a(n) = (n-1)^n/n*polylog(-n, 1/n) = 1/(n-1)*Sum(n^i*Sum((-1)^j*binomial(n+1, j)*(i-j+1)^n, j = 0 .. i), i = 0 .. n), n>1. - Vladeta Jovovic, Sep 26 2003
Prime p divides a(p-1) for p>2. - Alexander Adamchuk, Sep 19 2006
a(n) = A122020[n] / (n*(n-1)) for n>1. a(n) = A122778[n] / (n-1) for n>1. a(n) = ((n-1)^n)/n * A121376[n]/A121985[n] for n>1. - Alexander Adamchuk, Sep 19 2006
a(n) ~ exp(-1) * n! * n^(n-1) / log(n)^(n+1). - Vaclav Kotesovec, Jun 06 2022

A122020 Sum[k=0..n] Eulerian[n,k]*n^k.

Original entry on oeis.org

1, 6, 66, 1140, 28280, 948570, 41173776, 2238150600, 148570107264, 11804909261310, 1104566746764800, 120062928157552380, 14986973664751315968, 2127288759957421124610, 340440417300990616995840
Offset: 1

Views

Author

Alexander Adamchuk, Sep 12 2006, Sep 14 2006

Keywords

Comments

n divides a(n). 2^m divides a(n), where m(n) = {0,1,1,2,3,1,4,3,7,1,9,2,10,1,11,4,15,1,17,2,18,1,20,3,22,...}. p^k divides from a(p^k-1), a(p^k), a(p^k+1) for prime p>2 and integer k>0.

Crossrefs

Programs

  • Mathematica
    Table[Sum[Eulerian[n,k]*n^k,{k,0,n}],{n,1,25}]
    Flatten[{1, Table[(n-1)^(n+1)*PolyLog[-n, 1/n], {n, 2, 20}]}] (* Vaclav Kotesovec, Oct 16 2016 *)

Formula

a(n) = Sum[ Eulerian[n,k]*n^(n-k-1), {k,0,n} ] = n*A122778[n]. a(n) = n(n-1)*A086914[n] for n>1. a(n) = ((n-1)^(n+1)) * PolyLog[ -n, 1/n ] = ((n-1)^(n+1)) * Sum[ k^n/n^k, {k,1,Infinity} ] = ((n-1)^(n+1)) * A121376[n]/A121985[n] for n>1.
a(n) ~ exp(-1) * n! * n^(n+1) / log(n)^(n+1). - Vaclav Kotesovec, Jun 06 2022

A374896 Array read by falling antidiagonals: T(n,k) = denominator(Sum_{x>0} (x^n)/(k^x)); n >= 0 and k >= 2.

Original entry on oeis.org

1, 2, 1, 3, 4, 1, 4, 9, 2, 1, 5, 16, 27, 8, 1, 6, 25, 32, 27, 1, 1, 7, 36, 125, 128, 81, 4, 1, 8, 49, 27, 625, 128, 243, 4, 1, 9, 64, 343, 216, 3125, 512, 243, 16, 1, 10, 81, 256, 2401, 81, 3125, 1024, 729, 1, 1, 11, 100, 729, 2048, 16807, 972, 15625, 4096, 2187, 4, 1
Offset: 0

Views

Author

Mohammed Yaseen, Aug 03 2024

Keywords

Examples

			Array begins:
+-----+-----------------------------------------------+
| n\k |   2    3     4    5      6     7       8  ... |
+-----+-----------------------------------------------+
|  0  |   1    2     3    4      5     6       7  ... |
|  1  |   1    4     9   16     25    36      49  ... |
|  2  |   1    2    27   32    125    27     343  ... |
|  3  |   1    8    27  128    625   216    2401  ... |
|  4  |   1    1    81  128   3125    81   16807  ... |
|  5  |   1    4   243  512   3125   972  117649  ... |
|  6  |   1    4   243 1024  15625   486  823543  ... |
|  7  |   1   16   729 4096  78125 11664  823543  ... |
|  8  |   1    1  2187 2048 390625  2187 5764801  ... |
| ... | ...  ...   ...  ...    ...   ...     ...  ... |
+-----+-----------------------------------------------+
		

Crossrefs

Cf. A374895 (numerators).

Programs

  • PARI
    T(n,k) = denominator(polylog(-n, 1/k));
    matrix(7,7,n, k, T(n-1,k+1)) \\ Michel Marcus, Aug 04 2024

Formula

T(n,k) = denominator(polylog(-n, 1/k)).
T(n,k) = denominator(1/(k-1)^(n+1) * Sum_{m=1..n} A008292(n,m)*k^m).
T(0,k) = k-1.
T(1,k) = (k-1)^2.
T(2,k) = A277542(k-1).
T(n,2) = 1.
T(n,n) = A121985(n).
Showing 1-4 of 4 results.