OFFSET
1,3
COMMENTS
Also the NW-SE diagonal sums of A173398.
LINKS
Robert Israel, Table of n, a(n) for n = 1..4783
Index entries for linear recurrences with constant coefficients, signature (2,0,-2,2,0,-1).
FORMULA
a(n) = 1/2-(-1)^n/6+A057079(n+4)/6+A000045(n)/2 with g.f. -x*(-1+x+x^4)/ ((x-1) * (1+x) * (x^2+x-1) * (x^2-x+1)). - R. J. Mathar, Mar 04 2010
MAPLE
f:=gfun:-rectoproc({-a(n) - a(n + 1) + a(n + 2) - a(n + 3) - a(n + 4) + a(n + 5) + 1, a(0) = 0, a(1) = 1, a(2) = 1, a(3) = 2, a(4) = 2, a(5) = 3}, a(n), remember):
map(f, [$1..50]); # Robert Israel, Jun 11 2019
MATHEMATICA
CoefficientList[Series[-x*(-1+x+x^4)/((x-1)*(1+x)*(x^2+x-1)*(x^2-x+1)), {x, 0, 42}], x] (* Georg Fischer, Jun 11 2019 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Mark Dols, Feb 18 2010
EXTENSIONS
a(35) corrected by Georg Fischer, Jun 11 2019
STATUS
approved