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 1-5 of 5 results.

A065048 Largest unsigned Stirling number of the first kind: max_k(s(n+1,k)); i.e., largest coefficient of polynomial x*(x+1)*(x+2)*(x+3)*...*(x+n).

Original entry on oeis.org

1, 1, 3, 11, 50, 274, 1764, 13132, 118124, 1172700, 12753576, 150917976, 1931559552, 26596717056, 392156797824, 6165817614720, 102992244837120, 1821602444624640, 34012249593822720, 668609730341153280, 13803759753640704000, 298631902863216384000
Offset: 0

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Author

Henry Bottomley, Nov 06 2001

Keywords

Comments

n! <= a(n) <= (n+1)!; n <= a(n+1)/a(n) <= (n+1). - Max Alekseyev, Jul 17 2019

Examples

			a(4)=50 since polynomial is x^4 + 10*x^3 + 35*x^2 + 50*x + 24.
		

Crossrefs

Programs

  • Maple
    P:= x: A[0]:= 1:
    for n from 1 to 50 do
      P:= expand(P*(x+n));
      A[n]:= max(coeffs(P,x));
    od:
    seq(A[i],i=0..50); # Robert Israel, Jul 04 2016
  • Mathematica
    a[n_] := Max[Array[Abs[StirlingS1[n+1, #]]&, n+1]];
    Array[a, 100, 0] (* Griffin N. Macris, Jul 03 2016 *)
  • PARI
    a(n) = if (n==0, 1, vecmax(vector(n, k, abs(stirling(n+1, k, 1))))); \\ Michel Marcus, Jul 04 2016; corrected Jun 12 2022
    
  • Python
    from collections import Counter
    def A065048(n):
        c = {1:1}
        for k in range(1,n+1):
            d = Counter()
            for j in c:
                d[j] += k*c[j]
                d[j+1] += c[j]
            c = d
        return max(c.values()) # Chai Wah Wu, Jan 31 2024

Formula

For n in the interval [A309237(k)-1, A309237(k+1)-2], a(n) = |Stirling1(n+1,k)|. - Max Alekseyev, Jul 17 2019

A024417 s(n,a(n)) = max{s(n,k): k=1,2,...,n}, n >= 1, where s(n,k) = Stirling numbers of the second kind.

Original entry on oeis.org

1, 1, 2, 2, 3, 3, 4, 4, 4, 5, 5, 5, 6, 6, 6, 7, 7, 7, 8, 8, 8, 9, 9, 9, 10, 10, 10, 10, 11, 11, 11, 12, 12, 12, 12, 13, 13, 13, 14, 14, 14, 14, 15, 15, 15, 15, 16, 16, 16, 16, 17, 17, 17, 17, 18, 18, 18, 18, 19, 19, 19, 19, 20, 20, 20, 20, 21, 21, 21, 21, 22, 22, 22, 22, 23, 23, 23
Offset: 1

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Author

Keywords

Crossrefs

Cf. A002870 (maximum values), A008277 (triangle of Stirling numbers of the second kind).

Programs

  • Mathematica
    a[n_] := (m = Max[t = Table[ StirlingS2[n, k], {k, 1, n}]]; Position[t, m][[1, 1]]); Table[a[n], {n, 1, 77}] (* Jean-François Alcover, Nov 15 2011 *)

Formula

a(n) ~ n/LambertW(n) - 1 (conjecture). - Mats Granvik, Oct 16 2013

Extensions

More terms retrieved from the b-file by R. J. Mathar, Sep 17 2008

A325503 Heinz number of row n of the triangle of Stirling numbers of the second kind A008277.

Original entry on oeis.org

2, 4, 20, 884, 528844, 3460086044, 340672148731996, 477782556719729075524, 11694209380474301218263758996, 4967476846044415922850025924897606724, 43298471669920632729336800855543564573041217668, 7790810575556906457316064931238939360882160372451591124244
Offset: 1

Views

Author

Gus Wiseman, May 07 2019

Keywords

Comments

The Heinz number of a positive integer sequence (y_1,...,y_k) is prime(y_1)*...*prime(y_k).

Examples

			The sequence of terms together with their prime indices begins:
                              2: {1}
                              4: {1,1}
                             20: {1,1,3}
                            884: {1,1,6,7}
                         528844: {1,1,10,15,25}
                     3460086044: {1,1,15,31,65,90}
                340672148731996: {1,1,21,63,140,301,350}
          477782556719729075524: {1,1,28,127,266,966,1050,1701}
  11694209380474301218263758996: {1,1,36,255,462,2646,3025,6951,7770}
		

Crossrefs

Programs

  • Mathematica
    Times@@@Table[Prime[StirlingS2[n,k]],{n,1,10},{k,1,n}]

Formula

a(n) = Product_{i = 1..n} prime(A008277(n,i)).
A061395(a(n)) = A002870(n).
A056239(a(n)) = A000110(n).

A024717 Sum of max{S(i,j): 1<=j<=i} for i = 1,2,...,n, where S(i,j) are Stirling numbers of the second kind.

Original entry on oeis.org

1, 2, 5, 12, 37, 127, 477, 2178, 9948, 52473, 299203, 1678603, 10999915, 74436288, 495129561, 3777012165, 29485116951, 226947600351, 1936698603831, 17107631266510, 149618646613594, 1391581950147514, 13711650761944414, 134334225088016914, 1337497617263404414
Offset: 1

Views

Author

Keywords

Crossrefs

First differences are in A002870.

Programs

  • Maple
    A002870:= [seq(max(seq(combinat:-stirling2(i,j),j=1..i)),i=1..50)]:
    ListTools:-PartialSums(A002870); # Robert Israel, Jan 23 2018

A154416 Maximal Stirling numbers of the first kind.

Original entry on oeis.org

1, 1, 1, 2, 11, 35, 274, 1624, 13068, 118124, 1026576, 12753576, 120543840, 1931559552, 20313753096, 392156797824, 5056995703824, 102992244837120, 1583313975727488, 34012249593822720, 610116075740491776, 13803759753640704000, 284093315901811468800
Offset: 0

Views

Author

Roger L. Bagula, Jan 09 2009

Keywords

Crossrefs

Programs

  • Mathematica
    Table[Max[Table[StirlingS1[n, m], {m, 0, n}]], {n, 0, 30}]
  • PARI
    a(n) = vecmax(vector(n+1, m, stirling(n, m-1, 1))); \\ Michel Marcus, Sep 16 2016

Formula

a(n) = max_{m=0..n} StirlingS1(n,m).
Showing 1-5 of 5 results.