A046672 Expansion of 1/(1-2*x-3*x^2+2*x^3).
1, 2, 7, 18, 53, 146, 415, 1162, 3277, 9210, 25927, 72930, 205221, 577378, 1624559, 4570810, 12860541, 36184394, 101808791, 286449682, 805956949, 2267645362, 6380262207, 17951546602, 50508589101, 142111293594, 399845261287, 1125007225154
Offset: 0
Links
- Iain Fox, Table of n, a(n) for n = 0..2226
- Richard M. Low and Ardak Kapbasov, Non-Attacking Bishop and King Positions on Regular and Cylindrical Chessboards, Journal of Integer Sequences, Vol. 20 (2017), Article 17.6.1, Table 6.
- Index entries for linear recurrences with constant coefficients, signature (2, 3, -2).
Programs
-
PARI
first(n) = Vec(1/(1-2*x-3*x^2+2*x^3) + O(x^n)) \\ Iain Fox, Dec 02 2017
Formula
a(n) = 2*a(n-1) + 3*a(n-2) - 2*a(n-3), n > 2. - Iain Fox, Dec 02 2017