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.

A271638 The total sum of the cubes of all parts of all compositions of n.

Original entry on oeis.org

1, 10, 48, 170, 512, 1398, 3580, 8770, 20808, 48206, 109652, 245850, 544864, 1196134, 2605164, 5636210, 12124280, 25952382, 55312516, 117440650, 248512656, 524288150, 1103102108, 2315255970, 4848615592, 10133438638, 21139292340, 44023414970, 91536490688
Offset: 1

Views

Author

R. J. Mathar, Apr 11 2016

Keywords

Examples

			The two compositions of n=2 are 2 and 1+1. The total sum of the cubes is a(2) = 2^3+1^3+1^3 = 10.
		

Crossrefs

Cf. A027992 (sum of squares).

Programs

  • Mathematica
    Table[(13 n - 36) 2^(n - 1) + 6 n + 18, {n, 29}] (* or *)
    Rest@ CoefficientList[Series[x (1 + 4 x + x^2)/((1 - 2 x) (1 - x))^2, {x, 0, 29}], x] (* Michael De Vlieger, Apr 11 2016 *)
  • PARI
    x='x+O('x^99); Vec(x*(1+4*x+x^2)/((2*x-1)*(1-x))^2) \\ Altug Alkan, Apr 11 2016
    
  • Python
    for n in range(1,50):print((13*n-36)*2**(n-1)+6*n+18) # Soumil Mandal, Apr 11 2016

Formula

G.f.: x*(1 + 4*x + x^2)/((1 - 2*x)*(1 - x))^2.
a(n) = (13*n - 36)*2^(n - 1) + 6*n + 18.