Search: id:A026127
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%I A026127
%S A026127 1,4,20,110,608,3409,19304,110187,632960,3654915,21195716,123365099,
%T A026127 720240584,4216176575,24738092400,145444454754,856662911136,
%U A026127 5053815390148,29857490333880,176624209891024
%N A026127 a(n) = T(2n-1,n-1), where T is the array in A026120.
%o A026127 PARI programs from R. J. Mathar:
%o A026127 A026300(n,k)={ if(n<0 || k < 0, return(0) ;) ; if(n<=1, 1, if(k==0, 1, 
               if(k<n, A026300(n-1,k-2)+A026300(n-1,k-1)+A026300(n-1,k), A026300(n-1,
               n-2)+A026300(n-1,n-1)) ;) ;) ; }
%o A026127 A026300(n,k)={ if(n<0 || k < 0, return(0) ;) ; if(n<=1, 1, if(k==0, 1, 
               sum(i=0,k/2, binomial(n,2*i+n-k)*(binomial(2*i+n-k,i)-binomial(2*i+n-k,
               i-1))) ;) ;) ; }
%o A026127 A026105(n,k)={ if(k==0 || n<=1, 1, A026300(n,k)-A026300(n-1,k-1) ;) ; 
               }
%o A026127 A026120(n,k)={ if(n<=1, if(k== -1 || k < n, 1, 0), A026105(n+1,k+1)-A026105(n,
               k) ;) ; }
%o A026127 A026127(n)={ A026120(2*n-1,n-1) ; } { /* test for(i=0,7, for(j=0,i, print(A026300(i,
               j))) ; print(";") ;) ; */ /* test for(i=-1,7, for(j=-1,i, print(A026120(i,
               j))) ; print(";") ;) ; */ for(n=1,20, print(n," ",A026127(n))) ; 
               }
%Y A026127 Sequence in context: A061709 A135159 A020084 this_sequence A153295 A006770 
               A158827
%Y A026127 Adjacent sequences: A026124 A026125 A026126 this_sequence A026128 A026129 
               A026130
%K A026127 nonn
%O A026127 1,2
%A A026127 Clark Kimberling (ck6(AT)evansville.edu)
%E A026127 Corrected by R. J. Mathar, Oct 26 2006

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