OFFSET
2,1
LINKS
Harry J. Smith, Table of n, a(n) for n = 2..200
F. v. Lamoen, Wave sequences
Index entries for linear recurrences with constant coefficients, signature (2,3,-1,-1).
FORMULA
a(n) = 2*a(n-1) + 3*a(n-2) - a(n-3) - a(n-4). - Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Mar 22 2003
From R. J. Mathar, Jul 15 2009: (Start)
G.f.: -2*x^2*(-1+x+x^2)/((1+x)*(x^3-3*x+1)).
a(n) = 2*A006357(n-3). (End)
MATHEMATICA
LinearRecurrence[{2, 3, -1, -1}, {2, 2, 8, 20}, 30] (* Harvey P. Dale, Aug 31 2016 *)
PROG
(PARI) { for (n=2, 200, if (n>5, a=2*a1 + 3*a2 - a3 - a4; a4=a3; a3=a2; a2=a1; a1=a, if (n==2, a=a4=2, if (n==3, a=a3=2, if (n==4, a=a2=8, a=a1=20)))); write("b060823.txt", n, " ", a); ) } \\ Harry J. Smith, Jul 12 2009
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Jason Earls, May 01 2001
STATUS
approved