OFFSET
1,2
LINKS
Index entries for linear recurrences with constant coefficients, signature (1,0,0,1,-1).
FORMULA
From Colin Barker, May 14 2012: (Start)
G.f.: x^2*(3+2*x+2*x^2+x^3)/((1-x)^2*(1+x)*(1+x^2)).
a(n) = (-5+(-1)^n-i*(-i)^n+i*i^n+8*n)/4 where i=sqrt(-1). (End)
From Wesley Ivan Hurt, Jun 04 2016: (Start)
a(n) = a(n-1) + a(n-4) - a(n-5) for n>5.
E.g.f.: (2 - sin(x) + (4*x - 3)*sinh(x) + (4*x - 2)*cosh(x))/2. - Ilya Gutkovskiy, Jun 04 2016
Sum_{n>=2} (-1)^n/a(n) = (8-sqrt(2))*log(2)/16 + sqrt(2)*log(2+sqrt(2))/8 - (3-sqrt(2))*Pi/16. - Amiram Eldar, Dec 23 2021
MAPLE
A047485:=n->(-5+I^(2*n)-I*(-I)^n+I*I^n+8*n)/4: seq(A047485(n), n=1..100); # Wesley Ivan Hurt, Jun 04 2016
MATHEMATICA
Select[Range[0, 120], MemberQ[{0, 3, 5, 7}, Mod[#, 8]]&] (* Harvey P. Dale, May 20 2011 *)
PROG
(Magma) [n : n in [0..150] | n mod 8 in [0, 3, 5, 7]]; // Wesley Ivan Hurt, Jun 04 2016
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
STATUS
approved