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.

A293954 First differences of A055612.

Original entry on oeis.org

1, 4, 26, 318, 8362, 518136, 79762944, 31347878526, 31875040276682, 84415672202652576, 584440009839756835096, 10604211348847550536329728, 505234836942870203845022012928, 63320076924994011498092218964764672, 20908605974267058444111310750652481533952
Offset: 0

Views

Author

N. J. A. Sloane, Oct 30 2017, following a suggestion from Joerg Arndt

Keywords

Crossrefs

Programs

A293955 Partial sums of A055612.

Original entry on oeis.org

1, 3, 9, 41, 391, 9103, 535951, 80825743, 31508994061, 31937977439061, 84479516648536637, 584608936935076469309, 10605380482241904040731709, 505256047119225750718027007037, 63321087426482869467351750978047037, 20908732615936655362731019703436410620989
Offset: 0

Views

Author

N. J. A. Sloane, Oct 30 2017

Keywords

Crossrefs

Programs

  • Maple
    ListTools:-PartialSums([seq(mul(binomial(n,m)+1,m=1..n),n=0..20)]); # Robert Israel, Oct 30 2017
  • Mathematica
    Accumulate@ Array[Product[1 + Binomial[#, m], {m, #}] &, 16, 0] (* Michael De Vlieger, Oct 30 2017 *)

A217716 Duplicate of A129824.

Original entry on oeis.org

2, 4, 12, 64, 700, 17424, 1053696, 160579584, 62856336636, 63812936890000, 168895157342195152, 1169048914836855865344, 21209591746609937928524800, 1010490883477487017627972550656, 126641164340871500483202065902080000
Offset: 0

Views

Author

Jon Perry, Mar 21 2013

Keywords

Comments

Number of words less than or equal to the concatenation of the n-th row of Pascal's Triangle.
a(n) = 2 * A055612(n). - Reinhard Zumkeller, Jan 31 2015
Same as A129824. - Georg Fischer, Oct 14 2018

Examples

			Row 2 is 1 2 1 and we have 000, 001, 010, 011, 020, 021, 100, 101, 110, 111, 120 and 121 so a(2)=12.
		

Programs

  • Mathematica
    Table[Product[Binomial[n, k] + 1, {k, 0, n}], {n, 0, 15}] (* T. D. Noe, Mar 21 2013 *)

Formula

a(n) = Product_{k=0..n} (binomial(n,k) + 1).

A129824 a(n) = Product_{k=0..n} (1 + binomial(n,k)).

Original entry on oeis.org

2, 4, 12, 64, 700, 17424, 1053696, 160579584, 62856336636, 63812936890000, 168895157342195152, 1169048914836855865344, 21209591746609937928524800, 1010490883477487017627972550656, 126641164340871500483202065902080000, 41817338589698457759723104703370865147904
Offset: 0

Views

Author

Henry Gould, Jun 03 2007

Keywords

Comments

A product analog of the binomial expansion.
The sequence is a special case of a(n) = Product_{k=0..n} (1 + binomial(n,k)*x^k).
Let C be a collection of subsets of an n-element set S. Then a(n) is the number of possible shapes K = (k_0, ..., k_n) of C, where k_i is the number of i-element subsets of S in C. - Gabriel Cunningham (oeis(AT)gabrielcunningham.com), Nov 08 2007

Examples

			a(4) = (1+1)(1+4)(1+6)(1+4)(1+1) = 2*5*7*5*2 = 700.
		

References

  • H. W. Gould, A product analog of the binomial expansion, unpublished manuscript, Jun 03 2007.

Crossrefs

Programs

  • Magma
    A129824:= func< n | (&*[1 + Binomial(n,k): k in [0..n]]) >;
    [A129824(n): n in [0..20]]; // G. C. Greubel, Apr 26 2024
    
  • Mathematica
    Table[Product[1 + Binomial[n,k], {k,0,n}], {n,0,15}] (* Vaclav Kotesovec, Oct 27 2017 *)
  • PARI
    { a(n) = prod(k=0,n, 1 + binomial(n,k))}
    for(n=0,15,print1(a(n),", ")) \\ Paul D. Hanna, Oct 27 2017
    
  • SageMath
    def A129824(n): return product(1 + binomial(n,k) for k in range(n+1))
    [A129824(n) for n in range(21)] # G. C. Greubel, Apr 26 2024

Formula

a(n) = 2*A055612(n). - Reinhard Zumkeller, Jan 31 2015
a(n) ~ exp(n^2/2 + n - 1/12) * A^2 / (n^(n/2 + 1/3) * 2^((n-3)/2) * Pi^((n+1)/2)), where A is the Glaisher-Kinkelin constant A074962. - Vaclav Kotesovec, Oct 27 2017

Extensions

Corrected and extended by Vaclav Kotesovec, Oct 27 2017

A338772 The number of different probabilities p for which a coin that lands heads with probability p can, using n flips, perfectly model one flip of a fair coin.

Original entry on oeis.org

1, 3, 19, 271, 8635, 623533
Offset: 1

Views

Author

H. Tracy Hall, Nov 08 2020

Keywords

Comments

This counts the distinct roots in the range 0 to 1 occurring among a set of degree-n polynomials the number of which is given by A055612. The 2^n possible outcomes of n coin flips are divided into n + 1 classes depending on how many times heads comes up, and there is one polynomial for each way of deciding how many of each class goes on which side of the partition of outcomes that will model a fair coin flip.

Examples

			For n = 2 the a(2) = 3 different values of p are, in increasing order:
1 - sqrt(1/2), which can model a fair flip with the partition (HH, HT, TH), (TT);
1/2, which can model a fair flip with the partition (HH, HT), (TH, TT) (i.e., by ignoring the second flip); and
sqrt(1/2), which can model a fair flip with the partition (HH), (HT, TH, TT).
		

Programs

  • SageMath
    P.

    = QQ[] def polystream(nn, pol=P(0), kk=0): if kk >= nn: yield pol - 1 else: for ii in sxrange(binomial(nn, kk) + 1): for xx in polystream(nn, pol + 2 * ii * p^kk * (1-p)^(nn-kk), kk + 1): yield xx def calculate(nn): solutions = Set() for pol in polystream(nn): rootlist = [xx[0] for xx in pol.roots(ring=QQbar)] for root in rootlist: if root.real() == root and 0 <= root <= 1: solutions += Set([root]) return len(solutions)

Showing 1-5 of 5 results.