%I A023427
%S A023427 1,1,1,1,1,2,4,7,11,17,28,49,87,152,262,453,794,1408,
%T A023427 2507,4462,7943,14179,25415,45713,82398,148731,268859,
%U A023427 486890,883411,1605582,2922259,5325377,9716564
%N A023427 Generalized Catalan Numbers.
%t A023427 Clear[ a ]; a[ 0 ]=1; a[ n_Integer ] := a[ n ]=a[ n-1 ]+Sum[ a[ k ]*a[ 
               n-4-k ], {k, 1, n-4} ];
%Y A023427 Cf. A000108, A001006, A004148, A006318.
%Y A023427 Sequence in context: A023428 A093911 A152398 this_sequence A129929 A073738 
               A137631
%Y A023427 Adjacent sequences: A023424 A023425 A023426 this_sequence A023428 A023429 
               A023430
%K A023427 nonn,easy
%O A023427 0,6
%A A023427 Olivier Gerard (olivier.gerard(AT)gmail.com)