OFFSET
0,4
COMMENTS
Column 0 and column 1 are equal for n>0.
FORMULA
Let q=4; the g.f. of column k of P^m (ignoring leading zeros) equals: 1 + Sum_{n>=1} (m*q^k)^n/n! * Product_{j=0..n-1} L(q^j*x) where L(x) satisfies: x = Sum_{n>=1} -(-1)^n/n!*Product_{j=0..n-1} L(q^j*x); L(x) equals the g.f. of column 0 of the matrix log of P (A111849).
EXAMPLE
Let q=4; the g.f. of column k of matrix power P^m is:
1 + (m*q^k)*L(x) + (m*q^k)^2/2!*L(x)*L(q*x) +
(m*q^k)^3/3!*L(x)*L(q*x)*L(q^2*x) +
(m*q^k)^4/4!*L(x)*L(q*x)*L(q^2*x)*L(q^3*x) + ...
where L(x) satisfies:
x = L(x) - L(x)*L(q*x)/2! + L(x)*L(q*x)*L(q^2*x)/3! -+ ...
and L(x) = x + 4/2!*x^2 + 56/3!*x^3 + 1728/4!*x^4 +...(A111849).
Thus the g.f. of column 0 of matrix power P^m is:
1 + m*L(x) + m^2/2!*L(x)*L(4*x) + m^3/3!*L(x)*L(4*x)*L(4^2*x) +
m^4/4!*L(x)*L(4*x)*L(4^2*x)*L(4^3*x) + ...
Triangle P begins:
1;
1,1;
4,4,1;
40,40,16,1;
1040,1040,544,64,1;
78240,78240,48960,8320,256,1;
18504256,18504256,13110400,2878720,131584,1024,1; ...
where P^4 shifts columns left and up one place:
1;
4,1;
40,16,1;
1040,544,64,1;
78240,48960,8320,256,1; ...
PROG
(PARI) P(n, k, q=4)=local(A=Mat(1), B); if(n<k || k<0, 0, for(m=1, n+1, B=matrix(m, m); for(i=1, m, for(j=1, i, if(j==i, B[i, j]=1, if(j==1, B[i, j]=(A^q)[i-1, 1], B[i, j]=(A^q)[i-1, j-1])); )); A=B); return(A[n+1, k+1]))
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
Paul D. Hanna, Aug 23 2005
STATUS
approved