%I A099508
%S A099508 0,1,1,3,3,8,9,21,25,54,68,139,183,358,489,924,1301,2390,3450,6194,9126,
%T A099508 16080,24093,41805,63507,108817,167188,283533,439689,739391,1155384,
%U A099508 1929504,3033991,5038089,7962758,13161067,20889012,34394215,54778872
%N A099508 A transform of the Jacobsthal numbers.
%C A099508 A transform of A001045 under the mapping g(x)->(1/(1+x^3))g(x/(1+x^3)).
%F A099508 G.f.: x/(1-x-2x^2+2x^3-x^4+x^6); a(n)=a(n-1)+2a(n-2)-2a(n-3)+a(n-4)-a(n-6); 
               a(n)=sum{k=0..floor(n/3), binomial(n-2k, k)(-1)^k*J(n-3k)}.
%Y A099508 Cf. A099505.
%Y A099508 Sequence in context: A092549 A022663 A092481 this_sequence A141577 A123315 
               A052407
%Y A099508 Adjacent sequences: A099505 A099506 A099507 this_sequence A099509 A099510 
               A099511
%K A099508 easy,nonn
%O A099508 0,4
%A A099508 Paul Barry (pbarry(AT)wit.ie), Oct 20 2004