4,1

G.f. -(1+x^2+4*x^3) + (1-x+x^3)*c(x) with the g.f. c(x):=(1-sqrt(1-4*x))/(2*x) of A000108 (Catalan).

Cf. A071726 (second diagonal of A115127 for n>=3 with g.f. -(1+x+3*x^2)+(1+x^2)*c(x)).

Sequence in context: A034127 A005052 A057344 this_sequence A098684 A064012 A063154

Adjacent sequences: A115131 A115132 A115133 this_sequence A115135 A115136 A115137

nonn,easy

Wolfdieter Lang (wolfdieter.lang_AT_physik_DOT_uni-karlsruhe_DOT_de), Jan 13 2006