%I A115512
%S A115512 1,1,1,0,0,1,0,0,0,1,0,1,0,0,1,0,0,0,0,0,1,0,0,0,0,0,0,1,0,0,1,0,0,0,0,
%T A115512 1,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,1,0,0,0,1,0,0,0,0,0,0,1,0,0,0,0,
%U A115512 0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,1,0,0,0,0,0,0,0,0,1
%N A115512 Number triangle (1,x)+(x,x^3) expressed in terms of Riordan arrays.
%C A115512 Row sums are periodic {1,2,1}. Diagonal sums are periodic {1,1,1,0}. 
               Inverse is A115513.
%F A115512 Column k has g.f. x^k+x^(3k+1); Number triangle T(n, k)=if(n=k, 1, 0) 
               OR if(n=3k+1, 1, 0).
%e A115512 Triangle begins
%e A115512 1,
%e A115512 1, 1,
%e A115512 0, 0, 1,
%e A115512 0, 0, 0, 1,
%e A115512 0, 1, 0, 0, 1,
%e A115512 0, 0, 0, 0, 0, 1,
%e A115512 0, 0, 0, 0, 0, 0, 1,
%e A115512 0, 0, 1, 0, 0, 0, 0, 1,
%e A115512 0, 0, 0, 0, 0, 0, 0, 0, 1,
%e A115512 0, 0, 0, 0, 0, 0, 0, 0, 0, 1,
%e A115512 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1,
%e A115512 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1,
%e A115512 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1,
%e A115512 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1,
%e A115512 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1,
%e A115512 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1,
%e A115512 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1,
%e A115512 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1,
%e A115512 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1,
%e A115512 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1,
%e A115512 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1
%Y A115512 Sequence in context: A096606 A128190 A128189 this_sequence A115513 A133080 
               A010815
%Y A115512 Adjacent sequences: A115509 A115510 A115511 this_sequence A115513 A115514 
               A115515
%K A115512 easy,nonn,tabl
%O A115512 0,1
%A A115512 Paul Barry (pbarry(AT)wit.ie), Jan 23 2006