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.

A138382 First differences of A138380. Second differences of A138377.

Original entry on oeis.org

1, -3, -1, -2, -4, 12, 4, 8, 16, -48, -16, -32, -64, 192, 64, 128, 256, -768, -256, -512, -1024, 3072, 1024, 2048, 4096, -12288, -4096, -8192, -16384, 49152, 16384, 32768, 65536, -196608, -65536, -131072, -262144, 786432, 262144, 524288, 1048576, -3145728
Offset: 0

Views

Author

Paul Curtz, May 08 2008

Keywords

Crossrefs

Programs

  • Mathematica
    Differences[LinearRecurrence[{0,0,0,-4},{0,1,3,2},60],2] (* Harvey P. Dale, Mar 19 2012 *)
    LinearRecurrence[{0, 0, 0, -4},{1, -3, -1, -2},42] (* Ray Chandler, Aug 03 2015 *)

Formula

a(n) = -4*a(n-4).

Extensions

Definition corrected by R. J. Mathar, May 09 2008
More terms from Harvey P. Dale, Mar 19 2012

A138377 a(0) = 0, a(1) = 1, a(2) = 3, a(3) = 2; thereafter a(n) = -4*a(n-4).

Original entry on oeis.org

0, 1, 3, 2, 0, -4, -12, -8, 0, 16, 48, 32, 0, -64, -192, -128, 0, 256, 768, 512, 0, -1024, -3072, -2048, 0, 4096, 12288, 8192, 0, -16384, -49152, -32768, 0, 65536, 196608, 131072, 0, -262144, -786432, -524288, 0, 1048576, 3145728, 2097152, 0, -4194304, -12582912, -8388608, 0, 16777216, 50331648
Offset: 0

Views

Author

Paul Curtz, May 08 2008

Keywords

Comments

First and third differences have only 2^n's.

Crossrefs

Programs

  • Mathematica
    LinearRecurrence[{0,0,0,-4},{0,1,3,2},60] (* Harvey P. Dale, Mar 19 2012 *)
  • PARI
    x='x+O('x^25); Vec(x*(1+x)*(2*x+1)/((1-2*x+2*x^2)*(1+2*x+2*x^2))) \\ G. C. Greubel, Feb 20 2017

Formula

From R. J. Mathar, May 09 2008: (Start)
O.g.f.: x*(1+x)*(2*x+1)/((1-2*x+2*x^2)*(1+2*x+2*x^2)).
a(n) = (5*A009545(n) - A108520(n))/4. (End)
Showing 1-2 of 2 results.