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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A290351 Euler transform of the Bell numbers (A000110).

Original entry on oeis.org

1, 1, 3, 8, 26, 88, 340, 1411, 6417, 31474, 166242, 939646, 5659613, 36158227, 244049562, 1733702757, 12919475840, 100690425442, 818554392962, 6924577964036, 60828588178031, 553821749290234, 5217264062756556, 50776256646839085, 509823607380230570
Offset: 0

Views

Author

Alois P. Heinz, Jul 28 2017

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n) option remember; `if`(n=0, 1, add(
          b(n-j)*binomial(n-1, j-1), j=1..n))
        end:
    a:= proc(n) option remember; `if`(n=0, 1, add(add(d*
          b(d), d=numtheory[divisors](j))*a(n-j), j=1..n)/n)
        end:
    seq(a(n), n=0..30);
  • Mathematica
    b[n_]:=b[n]=If[n==0, 1, Sum[b[n - j] Binomial[n - 1, j - 1], {j, n}]]; a[n_]:=a[n]=If[n==0, 1, Sum[Sum[d*b[d], {d, Divisors[j]}] a[n - j], {j, n}]/n]; Table[a[n], {n, 0, 50}] (* Indranil Ghosh, Jul 28 2017, after Maple code *)

A327432 Smallest k > 0, such that A000110(k) is divisible by n, if such a number exists, otherwise 0.

Original entry on oeis.org

1, 2, 4, 5, 3, 8, 6, 0, 8, 8, 31, 8, 5, 20, 4, 0, 22, 8, 9, 8, 9, 53, 8, 0, 10, 5, 17, 20, 6, 8, 57, 0, 95, 26, 35, 8, 12, 59, 34, 0, 66, 35, 56, 53, 8, 8, 12, 0, 20, 56, 22, 5, 9, 17, 245, 0, 9, 104, 78, 8, 20, 89, 47, 0, 61, 95, 28, 29, 8, 35, 43, 0, 43, 125
Offset: 1

Views

Author

Vaclav Kotesovec, Sep 10 2019

Keywords

Comments

a(8*j) = 0.

Crossrefs

A361380 Sum over the j-th term of the (n-j)-th inverse binomial transform of the Bell numbers (A000110) for all j in [n].

Original entry on oeis.org

1, 2, 3, 6, 17, 56, 215, 922, 4305, 21894, 119539, 696632, 4314925, 28237146, 194602079, 1407456694, 10649642837, 84100177424, 691474151187, 5907288773554, 52340230286509, 480153099982726, 4553711640946919, 44584683333637168, 450075389309517849
Offset: 0

Views

Author

Alois P. Heinz, Mar 09 2023

Keywords

Crossrefs

Antidiagonal sums of A361781.

Programs

  • Maple
    a:= n-> add(add(binomial(i, j)*(i-n)^(i-j)*combinat[bell](j), j=0..i), i=0..n):
    seq(a(n), n=0..25);
    # second Maple program:
    a:= n-> add(i!*coeff(series(exp(exp(x)-(n-i)*x-1), x, i+1), x, i), i=0..n):
    seq(a(n), n=0..25);
    # third Maple program:
    b:= proc(n, m) option remember;
         `if`(n=0, 1, b(n-1, m+1)+m*b(n-1, m))
        end:
    a:= n-> add(b(i, i-n), i=0..n):
    seq(a(n), n=0..25);
  • Python
    from math import comb
    from sympy import bell
    def A361380(n): return sum(comb(i,j)*(i-n)**(i-j)*bell(j) for i in range(n+1) for j in range(i+1)) # Chai Wah Wu, Apr 05 2023

Formula

a(n) = Sum_{i=0..n} i! * [x^i] exp(exp(x)-(n-i)*x-1).
a(n) = Sum_{0<=j<=i<=n} binomial(i,j)*(i-n)^(i-j)*Bell(j).
a(n) mod 2 = A059841(n).

A361781 A(n,k) is the n-th term of the k-th inverse binomial transform of the Bell numbers (A000110); square array A(n,k), n>=0, k>=0, read by antidiagonals.

Original entry on oeis.org

1, 1, 1, 1, 0, 2, 1, -1, 1, 5, 1, -2, 2, 1, 15, 1, -3, 5, -3, 4, 52, 1, -4, 10, -13, 7, 11, 203, 1, -5, 17, -35, 36, -10, 41, 877, 1, -6, 26, -75, 127, -101, 31, 162, 4140, 1, -7, 37, -139, 340, -472, 293, -21, 715, 21147, 1, -8, 50, -233, 759, -1573, 1787, -848, 204, 3425, 115975
Offset: 0

Views

Author

Alois P. Heinz, Mar 23 2023

Keywords

Examples

			Square array A(n,k) begins:
    1,   1,   1,    1,     1,      1,       1,       1, ...
    1,   0,  -1,   -2,    -3,     -4,      -5,      -6, ...
    2,   1,   2,    5,    10,     17,      26,      37, ...
    5,   1,  -3,  -13,   -35,    -75,    -139,    -233, ...
   15,   4,   7,   36,   127,    340,     759,    1492, ...
   52,  11, -10, -101,  -472,  -1573,   -4214,   -9685, ...
  203,  41,  31,  293,  1787,   7393,   23711,   63581, ...
  877, 162, -21, -848, -6855, -35178, -134873, -421356, ...
		

Crossrefs

Columns k=0-5 give: A000110, A000296, A126617, A346738, A346739, A346740.
Rows n=0-2 give: A000012, A024000, A160457.
Main diagonal gives A290219.
Antidiagonal sums give A361380.
Cf. A108087.

Programs

  • Magma
    T:= func< n,k | (&+[(-k)^j*Binomial(n,j)*Bell(n-j): j in [0..n]]) >;
    A361781:= func< n,k | T(k, n-k) >;
    [A361781(n,k): k in [0..n], n in [0..12]]; // G. C. Greubel, Jun 12 2024
    
  • Maple
    A:= proc(n, k) option remember; uses combinat;
          add(binomial(n, j)*(-k)^j*bell(n-j), j=0..n)
        end:
    seq(seq(A(n, d-n), n=0..d), d=0..10);
    # second Maple program:
    b:= proc(n, m) option remember;
         `if`(n=0, 1, b(n-1, m+1)+m*b(n-1, m))
        end:
    A:= (n, k)-> b(n, -k):
    seq(seq(A(n, d-n), n=0..d), d=0..10);
  • Mathematica
    T[n_, k_]:= T[n, k]= If[k==0, BellB[n], Sum[(-k)^j*Binomial[n,j]*BellB[n-j], {j,0,n}]];
    A361781[n_, k_]= T[k, n-k];
    Table[A361781[n,k], {n,0,12}, {k,0,n}]//Flatten (* G. C. Greubel, Jun 12 2024 *)
  • SageMath
    def T(n,k): return sum( (-k)^j*binomial(n,j)*bell_number(n-j) for j in range(n+1))
    def A361781(n, k): return T(k, n-k)
    flatten([[A361781(n, k) for k in range(n+1)] for n in range(13)]) # G. C. Greubel, Jun 12 2024

Formula

E.g.f. of column k: exp(exp(x) - k*x - 1).
A(n,k) = Sum_{j=0..n} (-k)^j*binomial(n,j)*Bell(n-j).

A007311 Reversion of o.g.f. for Bell numbers (A000110) omitting a(0)=1.

Original entry on oeis.org

1, -2, 3, -5, 7, -14, 11, -66, -127, -992, -5029, -30899, -193321, -1285300, -8942561, -65113125, -494605857, -3911658640, -32145949441, -274036507173, -2419502677445, -22093077575496, -208364964369913, -2027216779571754, -20323053380033763, -209715614081160850
Offset: 1

Views

Author

Keywords

Comments

As the definition says, this entry deliberately omits the zero-th term 1. - N. J. A. Sloane, Jun 16 2021

References

  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Cf. A000110.

Programs

  • Maple
    read transforms; A := series(exp(exp(x)-1),x,60); SERIESTOLISTMULT(%); subsop(1=NULL,%); REVERT(%);
    # Alternative, using function CompInv from A357588:
    CompInv(26, n -> combinat:-bell(n)); # Peter Luschny, Oct 05 2022
  • PARI
    a(n)=if(n<1,0,polcoeff(serreverse(-1+serlaplace(exp(exp(x+x*O(x^n))-1))),n))

Formula

G.f. A(x) satisfies: A(x) = x - Sum_{k>=2} Bell(k) * A(x)^k. - Ilya Gutkovskiy, Apr 22 2020

Extensions

Signs corrected Dec 24 2001

A051140 a(n) = (A000110(n) - A000994(n+2))/2.

Original entry on oeis.org

0, 0, 0, 0, 1, 8, 47, 259, 1437, 8208, 48659, 300553, 1937958, 13052028, 91784452, 673328720, 5146726651, 40934788112, 338292605257, 2900716040495, 25769979503573, 236876549095324, 2249873611378525, 22053647698650293, 222832106687369092
Offset: 0

Views

Author

Keywords

Examples

			a(7) = (877 - 359)/2 = 259.
		

Crossrefs

A061462 The exact power of 2 that divides the n-th Bell number (A000110). Has period 12.

Original entry on oeis.org

1, 1, 2, 1, 1, 4, 1, 1, 4, 1, 1, 2, 1, 1, 2, 1, 1, 4, 1, 1, 4, 1, 1, 2, 1, 1, 2, 1, 1, 4, 1, 1, 4, 1, 1, 2, 1, 1, 2, 1, 1, 4, 1, 1, 4, 1, 1, 2, 1, 1, 2, 1, 1, 4, 1, 1, 4, 1, 1, 2, 1, 1, 2, 1, 1, 4, 1, 1, 4, 1, 1, 2, 1, 1, 2, 1, 1, 4, 1, 1, 4, 1, 1, 2, 1, 1, 2, 1, 1, 4, 1, 1, 4, 1, 1, 2, 1, 1, 2, 1, 1, 4, 1, 1, 4, 1, 1, 2
Offset: 0

Views

Author

Ahmed Fares (ahmedfares(AT)my-deja.com), Jun 10 2001

Keywords

Comments

{ Bell(n) mod 8 } is periodic with period 24, the period being (1 1 2 5 7 4 3 5 4 3 7 2 5 5 2 1 3 4 7 1 4 7 3 2). Hence the highest power of 2 dividing a Bell number is 4. - David W. Wilson, Jun 29 2001

Crossrefs

Cf. A000110.

Programs

  • Mathematica
    PadRight[{},120,{1,1,2,1,1,4,1,1,4,1,1,2}] (* Harvey P. Dale, Sep 24 2017 *)
  • PARI
    a(n)=[1, 1, 2, 1, 1, 4, 1, 1, 4, 1, 1, 2][n%12+1] \\ Charles R Greathouse IV, Jul 13 2016

A068939 a(n) = Bell(n^2), where Bell(n) are the Bell numbers, cf. A000110.

Original entry on oeis.org

1, 1, 15, 21147, 10480142147, 4638590332229999353, 3819714729894818339975525681317, 10726137154573358400342215518590002633917247281
Offset: 0

Views

Author

Karol A. Penson, Mar 08 2002

Keywords

Crossrefs

Cf. A000110.

Programs

  • Magma
    [Bell(n^2): n in [0..8]]; // Vincenzo Librandi, Jul 16 2013
    
  • Mathematica
    Table[BellB[n^2], {n, 0, 8}] (* Vincenzo Librandi, Jul 16 2013 *)
  • PARI
    for(n=0,50,print1(round(sum(i=0,1000,i^(n^2)/(i)!)/exp(1)),","))
    
  • Python
    from sympy import bell
    def A068939(n): return bell(n**2) # Chai Wah Wu, Jun 22 2022

Formula

a(n) = exp(-1)*Sum(k=>0, k^(n^2)/k!). - Benoit Cloitre, May 19 2002
Integral representation as n-th moment of a positive function on a positive half-axis, in Maple notation: a(n)=int(x^n*(sum(exp(-ln(x)^2/ (4*ln(k)))/(k!*sqrt(ln(k))), k=2..infinity)/ (2*exp(1)*sqrt(Pi)*x) +Dirac(1-x)/exp(1)), x=0..infinity), n=0, 1, ...

A092460 Numbers that are not Bell numbers (A000110).

Original entry on oeis.org

0, 3, 4, 6, 7, 8, 9, 10, 11, 12, 13, 14, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79
Offset: 1

Views

Author

N. J. A. Sloane, Mar 26 2004

Keywords

Programs

  • Mathematica
    With[{b=BellB[Range[6]]},Complement[Range[0,Last[b]],b]] (* Harvey P. Dale, Sep 05 2020 *)
  • Python
    from itertools import accumulate, islice
    def A092460_gen(): # generator of terms
        yield 0
        blist, b = (1,), 1
        while True:
            blist = list(accumulate(blist, initial=b))
            yield from range(b+1,b:=blist[-1])
    A092460_list = list(islice(A092460_gen(),30)) # Chai Wah Wu, Jun 22 2022

A113883 Indices of semiprime Bell numbers A000110.

Original entry on oeis.org

4, 6, 16, 31, 33, 49, 84
Offset: 1

Views

Author

Jonathan Vos Post, Jan 27 2006

Keywords

Comments

Semiprime analog of A051130 (indices of prime Bell numbers). These indices of semiprime Bell numbers include all values through B(120), which has 146 digits and at least 5 prime factors, the smallest being 71.

Examples

			a(1) = 4 because B(4) = 15 = 3 * 5.
a(2) = 6 because B(6) = 203 = 7 * 29.
a(3) = 16 because B(16) = 10480142147 = 241 * 43486067.
a(4) = 31 because B(31) = 10293358946226376485095653
= 11 * 935759904202397862281423.
a(5) = 33 because B(33) = 1629595892846007606764728147
= 5694673 * 286161451736738458339.
a(6) = 49 because B(49) =
10726137154573358400342215518590002633917247281
= 7615441337805454611187 *
1408472165798904899327563.
a(7) = 84 because B(84) is a 93-digit semiprime, whose smaller prime factor is 8429925224798761223.
		

Crossrefs

Formula

n such that A000110(n) is semiprime. n such that A000110(n) is in A001358.
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