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 1-1 of 1 results.

A172416 a(n) = 5*2^n/9 + 1/4 + (-1)^n*(n/6 + 7/36).

Original entry on oeis.org

1, 1, 3, 4, 10, 17, 37, 70, 144, 283, 571, 1136, 2278, 4549, 9105, 18202, 36412, 72815, 145639, 291268, 582546, 1165081, 2330173, 4660334, 9320680, 18641347, 37282707, 74565400, 149130814, 298261613, 596523241
Offset: 0

Views

Author

Paul Curtz, Feb 02 2010

Keywords

Comments

The sequence and the 1st, 2nd, 3rd etc. difference form the array
1, 1, 3, 4, 10, 17, 37, 70, 144, 283, 571, 1136,..
0, 2, 1, 6, 7, 20, 33, 74, 139, 288, 565, 1142, 2271,..
2, -1, 5, 1, 13, 13, 41, 65, 149, 277, 577, 1129, 2285,..
-3, 6, -4, 12, 0, 28, 24, 84, 128, 300, 552, 1156,...
where the sequence 1,2,5,12,.... = A045623 appears on the diagonal.

Programs

  • Magma
    [5*2^n/9 +1/4 +(-1)^n*(n/6+7/36): n in [0..40]]; // Vincenzo Librandi, Aug 05 2011

Formula

a(n) = a(n-1) + 3*a(n-2) - a(n-3) - 2*a(n-4).
a(n+1) - a(n) = A172285(n).
a(2n) = A164044(n).
a(2n+1) = A172447(n).
a(n+1) - 2*a(n) = (-1)^(n+1)*A008619(n).
G.f.: ( 1 - x^2 - x^3 ) / ( (2*x-1)*(x-1)*(1+x)^2 ).
Showing 1-1 of 1 results.