A187007 - OEIS

%I #4 Mar 30 2012 18:37:26

%S 1,3,12,69,538,5404,67092,997581,17337444,345547750,7778860028,

%T 195365725310,5418540898800,164556820433116,5432639292242576,

%U 193765826638479112,7426524928340527902,304439910637309354106

%N  A diagonal of triangle A187005.

%C  Definition of triangle: A187005(n,k) = [y^k] R_{n-1}(y+y^2) for k=1..n where R_n(y) is the n-th row polynomial for n>1 with R_1(y)=y.

%o  (PARI) {a(n)=local(Rn=y);for(m=1,n+2,Rn=subst(truncate(Rn),y,y+y^2+y*O(y^m)));polcoeff(Rn,n,y)}

%Y  Cf. A187005, A135081, A187006, A187008, A187009.

%K nonn

%O 1,2

%A _Paul D. Hanna_, Mar 02 2011