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.

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A348064 Coefficient of x^3 in expansion of n!* Sum_{k=0..n} binomial(x,k).

Original entry on oeis.org

1, -2, 25, -75, 1099, -4340, 79064, -382060, 8550916, -48306984, 1303568760, -8346754416, 266955481584, -1894529909376, 70785236377728, -547468189825536, 23610353987137536, -196402650598402560, 9679304091074250240, -85687212859582878720, 4785340778000524477440
Offset: 3

Views

Author

Seiichi Manyama, Sep 26 2021

Keywords

Crossrefs

Programs

  • PARI
    a(n) = n!*polcoef(sum(k=3, n, binomial(x, k)), 3);
    
  • PARI
    N=40; x='x+O('x^N); Vec(serlaplace(log(1+x)^3/(6*(1-x))))
    
  • Python
    from sympy.abc import x
    from sympy import ff, expand
    def A348064(n): return sum(ff(n,n-k)*expand(ff(x,k)).coeff(x**3) for k in range(3,n+1)) # Chai Wah Wu, Sep 27 2021

Formula

E.g.f.: (log(1 + x))^3/(6 * (1 - x)).

A081051 Stirling numbers of the first kind.

Original entry on oeis.org

0, 0, 1, -6, 35, -225, 1624, -13132, 118124, -1172700, 12753576, -150917976, 1931559552, -26596717056, 392156797824, -6165817614720, 102992244837120, -1821602444624640, 34012249593822720, -668609730341153280, 13803759753640704000, -298631902863216384000
Offset: 0

Views

Author

Paul Barry, Mar 05 2003

Keywords

Comments

Coefficient of x^3 in Product {k=0..(n-1), x-k}.

Crossrefs

Programs

  • Mathematica
    Table[StirlingS1[n, 3], {n, 1, 20}] (* Vaclav Kotesovec, Mar 03 2022 *)

Formula

E.g.f. (1+x)^(-1)*log(1+x)^2/2
a(n) = (-1)^n*det(S(i+3,j+2), 1 <= i,j <= n-2), where S(n,k) are Stirling numbers of the second kind and n>1. [Mircea Merca, Apr 06 2013]
a(n) ~ n! * (-1)^n * log(n)^2/2 * (1 + 2*gamma/log(n)), where gamma is the Euler-Mascheroni constant A001620. - Vaclav Kotesovec, Mar 03 2022

A081052 Difference of Stirling numbers of the first kind.

Original entry on oeis.org

0, 1, -4, 17, -85, 499, -3388, 26200, -227708, 2199276, -23382216, 271461816, -3418002432, 46399476096, -675622445184, 10504980616320, -173726527230720, 3045008035203840, -56389237652344320, 1100174877158791680, -22556707790402304000, 484876713643386624000
Offset: 0

Views

Author

Paul Barry, Mar 05 2003

Keywords

Crossrefs

Programs

  • Mathematica
    Table[StirlingS1[n,2]-StirlingS1[n,3],{n,30}] (* Harvey P. Dale, May 02 2012 *)
  • PARI
    for(n=1, 22, print1(stirling(n, 2) - stirling(n, 3),", ")) \\ Indranil Ghosh, Mar 11 2017

Formula

a(n) = s(n,2) - s(n,3), s(n,m) = signed Stirling number of the first kind.
E.g.f. (1+x)^-1 * (log(1+x) - (log(1+x)^2)/2).
Conjecture: a(n) +3*(n-1)*a(n-1) +(3*n^2-9*n+7)*a(n-2) +(n-2)^3*a(n-3)=0. - R. J. Mathar, Nov 24 2012

A309237 Records in the indices of largest unsigned Stirling number of first kind: a(n) = smallest m such that c(m,n) = max_{k=0,1...,m} c(m,k).

Original entry on oeis.org

0, 1, 2, 8, 25, 73, 204, 565, 1557, 4275, 11710, 32022, 87464, 238692, 650971, 1774466
Offset: 0

Views

Author

Max Alekseyev, Jul 17 2019

Keywords

Comments

Smallest m such that A065048(m-1) = c(m,n).
For k in the interval [a(n),a(n+1)-1], A065048(k-1) = c(k,n).
Ratio a(n+1)/a(n) seems to decrease and tend to exp(1) as n grows.

Examples

			n=2 is a value for index k delivering the maximum value of c(m,k) for each fixed m in the interval [a(2),a(3)-1] = [2,7]. Then, for m in [a(3),a(4)-1] = [8,24], the maximum is given by c(m,3), and so on.
		

Crossrefs

Programs

  • PARI
    { A309237(n) = my(t=prod(i=1,n-1,x+i+O(x^n)), m=n); while( polcoef(t,n-1)-polcoef(t,n-2) < 0, t*=x+m; m++); m; }

Extensions

a(14)-a(15) from Alexander Fritsch and Johann Peters, Dec 04 2024

A346945 Expansion of e.g.f. log( 1 + log(1 + x)^3 / 3! ).

Original entry on oeis.org

1, -6, 35, -235, 1834, -16352, 164044, -1830630, 22513326, -302700926, 4419167532, -69637654996, 1178377833424, -21315571470320, 410529985172400, -8388475139138320, 181270810764205440, -4130796696683135280, 99008773205008777760, -2490134250475836315120
Offset: 3

Views

Author

Ilya Gutkovskiy, Aug 08 2021

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 22; CoefficientList[Series[Log[1 + Log[1 + x]^3/3!], {x, 0, nmax}], x] Range[0, nmax]! // Drop[#, 3] &
    a[n_] := a[n] = StirlingS1[n, 3] - (1/n) Sum[Binomial[n, k] StirlingS1[n - k, 3] k a[k], {k, 1, n - 1}]; Table[a[n], {n, 3, 22}]

Formula

a(n) = Stirling1(n,3) - (1/n) * Sum_{k=1..n-1} binomial(n,k) * Stirling1(n-k,3) * k * a(k).
a(n) = Sum_{k=1..floor(n/3)} (-1)^(k-1) * (3*k)! * Stirling1(n,3*k)/(k * 6^k). - Seiichi Manyama, Jan 23 2025

A383164 Expansion of e.g.f. -log(1 - (exp(2*x) - 1)/2)^3 / 6.

Original entry on oeis.org

0, 0, 0, 1, 18, 255, 3555, 52290, 831684, 14405580, 271688580, 5562400800, 123123764808, 2933953637472, 74953425290016, 2044855241694720, 59361121229581440, 1827578437315965696, 59494057195888597248, 2042194772007257103360, 73731225467600254686720
Offset: 0

Views

Author

Seiichi Manyama, Apr 18 2025

Keywords

Crossrefs

Column k=3 of A383149.

Programs

  • PARI
    a(n) = sum(k=3, n, 2^(n-k)*stirling(n, k, 2)*abs(stirling(k, 3, 1)));

Formula

a(n) = Sum{k=3..n} 2^(n-k) * Stirling2(n,k) * |Stirling1(k,3)|.
a(n) ~ sqrt(Pi) * 2^(n - 1/2) * n^(n - 1/2) * log(n)^2 / (exp(n) * log(3)^n). - Vaclav Kotesovec, Apr 18 2025

A188881 Triangle of coefficients arising from an expansion of Integral( exp(exp(exp(x))), dx).

Original entry on oeis.org

1, 1, 1, 2, 3, 2, 6, 11, 12, 6, 24, 50, 70, 60, 24, 120, 274, 450, 510, 360, 120, 720, 1764, 3248, 4410, 4200, 2520, 720, 5040, 13068, 26264, 40614, 47040, 38640, 20160, 5040, 40320, 109584, 236248, 403704, 538776, 544320, 393120, 181440, 40320
Offset: 1

Views

Author

N. J. A. Sloane, Apr 14 2011

Keywords

Comments

Also the coefficients of the polynomials which are generated by the exponential generating function -log(1 + x*log(1 - t)). The polynomials might be called 'logarithmic polynomials'. Note also A003713, and A263634 for a different use of this term. See the paper of F. Qi for a related, but different family of polynomials. - Peter Luschny, Jul 11 2020
Edgar remarks that these coefficients are related to Stirling numbers of the second kind (cf. A008277).
The first column and the main diagonal are the factorials (A000142). The n-th entry on the first subdiagonal is A001710(n+1). The second column is A000254, the third column is 2*A000399, and the fourth column is 6*A000454. In general, the k-th column is (k-1)!*s(n,k), where s(n,k) is the unsigned Stirling number of the first kind. - Nathaniel Johnston, Apr 15 2011
With offset n=0, k=0 : triangle T(n,k), read by rows,given by T(n,k) = k*T(n-1, k-1) + n*T(n-1, k) with T(0, 0) = 1. - Philippe Deléham, Oct 04 2011

Examples

			Triangle begins:
1
1    1
2    3    2
6    11   12   6
24   50   70   60   24
120  274  450  510  360  120
...
		

Crossrefs

Programs

  • Maple
    S:=proc(n,k)global s:if(n=0 and k=0)then s[0,0]:=1:elif(n=0 or k=0)then s[n,k]:=0:elif(not type(s[n,k],integer))then s[n,k]:=(n-1)*S(n-1,k)+S(n-1,k-1):fi:return s[n,k]:end:
    T:=proc(n,k)return (k-1)!*S(n,k);end:
    for n from 1 to 6 do for k from 1 to n do print(T(n,k)):od:od: # Nathaniel Johnston, Apr 15 2011
    # With offset n = 0, k = 0:
    A188881 := (n, k) -> k!*abs(Stirling1(n+1, k+1)):
    seq(seq(A188881(n,k), k=0..n), n=0..8); # Peter Luschny, Oct 19 2017
    # Alternative:
    gf := -log(1 + x*log(1 - t)): ser := series(gf, t, 18):
    toeff := n -> n!*expand(coeff(ser, t, n)):
    seq(print(seq(coeff(toeff(n), x, k), k=1..n)), n=1..8); # Peter Luschny, Jul 10 2020
  • Mathematica
    Table[(k - 1)! * Sum[StirlingS2[i, k] * (-1)^(n - i) * StirlingS1[n, i], {i, 0, k}], {n, 9}, {k, n}] // Flatten (* Michael De Vlieger, Apr 17 2015 *)
  • Maxima
    T(n,k):=(k-1)!*sum(stirling2(i,k)*(-1)^(n-i)*stirling1(n,i),i,0,k); /* Vladimir Kruchinin, Apr 17 2015 */
    
  • PARI
    {T(n, k) = if( k<1 || k>n, 0, (n-1)! * polcoeff( (x / (1 - exp(-x * (1 + x * O(x^n)))))^n, n-k))}; /* Michael Somos, May 10 2017 */
    
  • PARI
    {T(n, k) = if( k<1 || n<0, 0, (k-1)! * sum(i=0, k, stirling(i, k, 2) * (-1)^(n-i) * stirling(n, i, 1)))}; /* Michael Somos, May 10 2017 */

Formula

T(n, k) = (k-1)!*Sum_{i=0..k}(Stirling2(i,k)*(-1)^(n-i)*Stirling1(n,i)) =
T(n, k) = Sum_{i=0..k}(W(i,k)*(-1)^(n-i)*Stirling1(n,i)), where W(n,k) is the Worpitzky triangle A028246. - Vladimir Kruchinin, Apr 17 2015.
T(n,k) = [x^k] n!*[t^n](-log(1 + x*log(1 - t))). - Peter Luschny, Jul 10 2020
T(n,k) = Sum_{m=0..n-k} abs(Stirling1(n-1,m+k-1))*(k+m-1)!/m!. - Vladimir Kruchinin, Jul 14 2025

Extensions

a(11)-a(45) from Nathaniel Johnston, Apr 15 2011

A381106 Expansion of e.g.f. -log(1-x)^3 * (exp(x) - 1) / 6.

Original entry on oeis.org

0, 0, 0, 0, 4, 40, 320, 2555, 21728, 200802, 2024510, 22221485, 264453750, 3396686865, 46873789235, 692049842575, 10889098371032, 181952854080860, 3218431205690356, 60087159752141449, 1180916015576750386, 24372799835934758327, 527084149497398472485, 11919591185373007970251
Offset: 0

Views

Author

Seiichi Manyama, Feb 14 2025

Keywords

Crossrefs

Programs

  • PARI
    a(n) = sum(k=0, n-1, binomial(n, k)*abs(stirling(k, 3, 1)));

Formula

a(n) = Sum_{k=0..n-1} binomial(n,k) * |Stirling1(k,3)|.
a(n) = A381022(n) - A000399(n).

A381108 Expansion of e.g.f. log(1-x)^2 * (exp(x) - 1) / (2 * (1-x)).

Original entry on oeis.org

0, 0, 0, 3, 30, 245, 2010, 17549, 165942, 1705584, 19024275, 229478689, 2981315139, 41545542818, 618579336284, 9804891730633, 164897938095108, 2933486106772376, 55047126101826453, 1086816606230786217, 22523274090016854661, 488907589907823010158, 11093875133012393113766
Offset: 0

Views

Author

Seiichi Manyama, Feb 14 2025

Keywords

Crossrefs

Programs

  • PARI
    a(n) = sum(k=0, n-1, binomial(n, k)*abs(stirling(k+1, 3, 1)));

Formula

a(n) = Sum_{k=0..n-1} binomial(n,k) * |Stirling1(k+1,3)|.
a(n) = A381024(n) - A000399(n+1).

A081103 Alternating sum of first three Stirling numbers of the first kind.

Original entry on oeis.org

0, 1, -4, 18, -95, 584, -4123, 32969, -294992, 2922956, -31791716, 376719892, -4832017320, 66713229192, -986611705584, 15561976320144, -260804276106624, 4628322010931328, -86710491660063744, 1710290952899283456, -35427639035553292800, 768970029545198092800
Offset: 0

Views

Author

Paul Barry, Mar 05 2003

Keywords

Crossrefs

Formula

a(n) = s(n, 1)-s(n, 2)+s(n, 3), s(n, m)= signed Stirling numbers of the first kind.
E.g.f.: (1+x)^(-1)*(log(1+x)-log(1+x)^2/2+log(1+x)^3/6).
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