A173222 Column 1 of triangle A173220.

0, 4, 18, 672, 51600, 6883920, 1399989780, 401060653056, 153389081849472, 75336980135472000, 46137556536570417600, 34425740593629308436480, 30717476677184291740437120, 32275806213061043955592058880

Offset

0,2

Comments

Triangle A173220 is the matrix log of triangle T = A173210, which satisfies: row n of T^n = row n of (I+D)^(n^2) where D is the lower diagonal matrix: D(n+1,n)=n+1.

Links

Table of n, a(n) for n=0..13.

Prog

(PARI) {a(n)=local(M=Mat(1), N, L=Mat(1), C=matrix(n+3, n+3, r, c, if(r==c, 1, if(r==c+1, c)))); for(i=1, n+2, N=M; M=matrix(#N+1, #N+1, r, c, if(r>=c, if(r<=#N, (N^(#N))[r, c], (C^((#M)^2))[r, c]))); L=sum(i=1, #M, -(M^0-M)^i/i); M=sum(i=0, #M, (L/#N)^i/i!); ); L[n+2, 2]/(n+2)}

Crossrefs

Cf. A173220, A173221, A173223, A173224.

Sequence in context: A354303 A114574 A295223 * A342467 A367533 A156491

Adjacent sequences: A173219 A173220 A173221 * A173223 A173224 A173225

Keyword

nonn

Author

Paul D. Hanna, Feb 12 2010

Status

approved