A105627 Column 1 of triangle A105626.
1, 6, 48, 480, 5736, 79584, 1256808, 22262640, 437315016, 9438589824, 222109617288, 5661445534800, 155427839133096, 4573268363775264, 143592923776842408, 4792636497324986160, 169456698405536983176
Offset: 0
Keywords
Programs
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PARI
{a(n)=local(R,M=matrix(n+2,n+2,m,j,if(m>=j,if(m==j,1,if(m==j+1,-2*j, polcoeff(1/sum(i=0,m-j,(2*i)!/i!/2^i*x^i)+O(x^m),m-j)))))^-3); R=(M+M^0)/2;for(i=1,floor(2*log(n+2)),R=(R+M*R^(-1))/2); return(if(n<0,0,R[n+2,2]))}
Comments