A131474 a(n) = ceiling(n/2)*ceiling(n^2/2).

0, 1, 2, 10, 16, 39, 54, 100, 128, 205, 250, 366, 432, 595, 686, 904, 1024, 1305, 1458, 1810, 2000, 2431, 2662, 3180, 3456, 4069, 4394, 5110, 5488, 6315, 6750, 7696, 8192, 9265, 9826, 11034, 11664, 13015, 13718, 15220, 16000, 17661

Offset: 0

Author

Mohammad K. Azarian, Jul 27 2007

Keywords

• nonn
• easy

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..10000
• Index entries for linear recurrences with constant coefficients, signature (1,3,-3,-3,3,1,-1).

Crossrefs

Cf. A000982, A004526, A008619, A033431, A059722.

Programs

Magma

[Ceiling(n/2)*Ceiling(n^2/2) : n in [0..50]]; // Vincenzo Librandi, Oct 01 2011

Mathematica

Table[Ceiling[n/2]*Ceiling[n^2/2], {n, 0, 50}] (* Paolo Xausa, Aug 21 2024 *)

PARI

a(n)=ceil(n/2)*ceil(n^2/2) \\ Charles R Greathouse IV, Jun 11 2015

Formula

From R. J. Mathar, Dec 19 2008: (Start)

G.f.: x*(1 + x + 5*x^2 + 2*x^4 + 3*x^3)/((1+x)^3*(x-1)^4).

a(n) = A000982(n)*A004526(n+1). (End)

a(2*n) = A033431(n). - Bernard Schott, Mar 29 2020

a(2*n-1) = A059722(n). - Michel Marcus, Mar 29 2020