OFFSET
1,4
COMMENTS
An auxiliary array for computing A088488.
LINKS
FORMULA
T(n,k) = n! / Product_{m=(n-floor((2n)/(3^k))) .. (n-floor((n)/(3^k)))} m.
EXAMPLE
The first rows of the triangular table:
1
1, 1
3, 2, 2
4, 6, 6, 6
5, 6, 24, 24, 24
30, 24, 120, 120, 120, 120
84, 120, 720, 720, 720, 720, 720
112, 720, 5040, 5040, 5040, 5040, 5040, 5040
1008, 6480, 40320, 40320, 40320, 40320, 40320, 40320, 40320
4320, 50400, 362880, 362880, 362880, 362880, 362880, 362880, 362880, 362880
...
PROG
(PARI)
A254876bi(n, k) = n! / prod(i=(n-((2*n)\(3^k))), (n-(n\(3^k))), i);
(Scheme)
(define (A254876bi n k) (/ (A000142 n) (mul A000027 (- n (floor->exact (/ (* 2 n) (expt 3 k)))) (- n (floor->exact (/ n (expt 3 k)))))))
(define (mul intfun lowlim uplim) (let multloop ((i lowlim) (res 1)) (cond ((> i uplim) res) (else (multloop (+ 1 i) (* res (intfun i)))))))
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
Antti Karttunen, Feb 09 2015
STATUS
approved