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.

A101096 Third differences of fifth powers (A000584).

Original entry on oeis.org

1, 29, 150, 390, 750, 1230, 1830, 2550, 3390, 4350, 5430, 6630, 7950, 9390, 10950, 12630, 14430, 16350, 18390, 20550, 22830, 25230, 27750, 30390, 33150, 36030, 39030, 42150, 45390, 48750, 52230, 55830, 59550, 63390, 67350, 71430, 75630, 79950, 84390, 88950
Offset: 1

Views

Author

Cecilia Rossiter, Dec 15 2004

Keywords

Comments

Original Name: Shells (nexus numbers) of shells of shells of the power of 5.
For n>=3 a(n) is equal to the number of functions f:{1,2,3,4,5}->{1,2,...,n} such that Im(f) contains 3 fixed elements. - Aleksandar M. Janjic and Milan Janjic, Feb 24 2007

Crossrefs

Cf. A069477.
Third differences of A000584, second differences of A022521, and first differences of A068236.
Cf. A101095 for other sequences related to MagicNKZ.
Cf. A001844.

Programs

  • Magma
    m:=40; R:=PowerSeriesRing(Integers(), m); Coefficients(R!( x*(x^4+26*x^3+66*x^2+26*x+1)/(1-x)^3)); // G. C. Greubel, Dec 01 2018
  • Mathematica
    MagicNKZ=Sum[(-1)^j*Binomial[n+1-z, j]*(k-j+1)^n, {j, 0, k+1}];Table[MagicNKZ, {n, 5, 5}, {z, 3, 3}, {k, 0, 34}]
    CoefficientList[Series[(-z^4-26z^3-66z^2-26z-1)/(z-1)^3, {z, 0, 200}], z] (* Vladimir Joseph Stephan Orlovsky, Jun 19 2011 *)
    Join[{1,29},Differences[Range[0,40]^5,3]] (* or *) LinearRecurrence[{3,-3,1},{1,29,150,390,750},40] (* Harvey P. Dale, Feb 02 2017 *)
  • PARI
    a(n)=if(n>2,60*n^2-180*n+150,28*n-27) \\ Charles R Greathouse IV, Oct 11 2015
    
  • Sage
    [sum([(-1)^j*binomial(3, j)*(k-j+1)^5 for j in range(min(k+2,4))]) for k in range(40)] # Danny Rorabaugh, Apr 27 2015
    

Formula

a(k+1) = MagicNKZ(5,k,3) where MagicNKZ(n,k,z) = Sum_{j=0..k+1} (-1)^j*binomial(n+1-z,j)*(k-j+1)^n. (Cf. A101095.)
a(n+1) = 30*(1 - 2*n + 2*n^2) for n>2.
a(n+3) = A069477(n). - Vladimir Joseph Stephan Orlovsky, Jun 19 2011
G.f.: x*(x^4+26*x^3+66*x^2+26*x+1)/(1-x)^3. - Colin Barker, Oct 17 2012
Sum_{n>=1} 1/a(n) = (Pi/60)*tanh(Pi/2) + 871/870. - Amiram Eldar, Jan 27 2022

Extensions

MagicNKZ material edited and SeriesAtLevelR material removed by Danny Rorabaugh, Apr 27 2015