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 1-2 of 2 results.

A027992 a(n) = 1*T(n,0) + 2*T(n,1) + ... + (2n+1)*T(n,2n), T given by A027926.

Original entry on oeis.org

1, 6, 22, 66, 178, 450, 1090, 2562, 5890, 13314, 29698, 65538, 143362, 311298, 671746, 1441794, 3080194, 6553602, 13893634, 29360130, 61865986, 130023426, 272629762, 570425346, 1191182338, 2483027970, 5167382530, 10737418242
Offset: 0

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Author

Keywords

Comments

Also total sum of squares of parts in all compositions of n (offset 1). Total sum of cubes of parts in all compositions of n is (13*n-36)*2^(n-1)+6*n+18 with g.f. x*(1+4x+x^2)/((2x-1)(1-x))^2, A271638; total sum of fourth powers of parts in all compositions of n is (75*n-316)*2^(n-1)+12*n^2+72*n+158 with g.f. x*(1+x)*(x^2+10*x+1)/((2*x-1)^2*(1-x)^3); total sum of fifth powers of parts in all compositions of n is (541*n-3060)*2^(n-1)+20*n^3+180*n^2+790*n+1530. - Vladeta Jovovic, Mar 18 2005
Let M = the 3 X 3 matrix [(1,0,0),(1,2,0),(1,3,2)] and column vector V = [1,1,1]. a(n) is the lower term in the product M^n * V.

Crossrefs

Programs

  • Mathematica
    M = {{1, 0, 0}, {1, 2, 0}, {1, 3, 2}};
    a[n_] := MatrixPower[M, n].{1, 1, 1} // Last;
    Table[a[n], {n, 0, 27}] (* Jean-François Alcover, Aug 12 2018, from PARI *)
  • PARI
    vector(40, n, n--; ([1,0,0;1,2,0;1,3,2]^n*[1,1,1]~)[3]) \\ Michel Marcus, Aug 06 2015

Formula

a(n) = 2^n*(3n-1)+2 = A048496(n+1)-1 = A053565(n+1)+2. - Ralf Stephan, Jan 15 2004
a(n) = 5*a(n-1)-8*a(n-2)+4*a(n-3). G.f.: (1+x)/((1-x)*(1-2*x)^2). - Colin Barker, Apr 04 2012

A053565 a(n) = 2^(n-1)*(3*n-4).

Original entry on oeis.org

-2, -1, 4, 20, 64, 176, 448, 1088, 2560, 5888, 13312, 29696, 65536, 143360, 311296, 671744, 1441792, 3080192, 6553600, 13893632, 29360128, 61865984, 130023424, 272629760, 570425344, 1191182336, 2483027968, 5167382528, 10737418240
Offset: 0

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Author

Barry E. Williams, Jan 17 2000

Keywords

References

  • A. H. Beiler, Recreations in the Theory of Numbers, Dover, N.Y., 1964, pp. 189, 194-196.

Crossrefs

Programs

  • GAP
    List([0..30], n-> 2^(n-1)*(3*n-4)) # G. C. Greubel, May 16 2019
  • Magma
    [2^(n-1)*(3*n-4): n in [0..30]]; // Vincenzo Librandi, Sep 26 2011
    
  • Mathematica
    Table[2^(n-1)*(3*n-4), {n,0,30}] (* G. C. Greubel, May 16 2019 *)
  • PARI
    vector(30, n, n--; 2^(n-1)*(3*n-4)) \\ G. C. Greubel, May 16 2019
    
  • Sage
    [2^(n-1)*(3*n-4) for n in (0..30)] # G. C. Greubel, May 16 2019
    

Formula

a(n) = 4*a(n-1) - 4*a(n-2), with a(0) = -2, a(1) = -1.
G.f.: -(2-7*x)/(1-2*x)^2. - Colin Barker, Apr 07 2012
E.g.f.: (3*x - 2)*exp(2*x). - G. C. Greubel, May 16 2019
Showing 1-2 of 2 results.