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A202189
Triangle T(n,k) = coefficient of x^n in expansion of x^k*(1+x+x^2)^(k*x) = sum(n>=k, T(n,k) x^n*k!/n!).
0
1, 0, 1, 6, 0, 1, 12, 24, 0, 1, -20, 60, 60, 0, 1, 540, 240, 180, 120, 0, 1, -882, 6300, 2100, 420, 210, 0, 1, -6720, -8736, 35280, 8960, 840, 336, 0, 1, 189936, 181440, 13608, 136080, 27720, 1512, 504, 0, 1
OFFSET
1,4
COMMENTS
Also the Bell transform of (n+1)!*Sum_{k=0..n}(Sum_{i=k..n-k}((-1)^(i-k)*S1(i,k)* binomial(i,n-k-i)/i!) where S1 are the Stirling cycle numbers A132393. For the definition of the Bell transform see A264428. - Peter Luschny, Jan 15 2016
FORMULA
T(n,m) = n!/m!*sum(k=0..n-m, (sum(i=k,n-m-k, (stirling1(i,k)*binomial(i,n-m-k-i))/i!))*m^k).
EXAMPLE
Triangle begins:
1
0, 1,
6, 0, 1,
12, 24, 0, 1,
-20, 60, 60, 0, 1,
540, 240, 180, 120, 0, 1,
-882, 6300, 2100, 420, 210, 0, 1
MATHEMATICA
Table[n!/m! Sum[Sum[(StirlingS1[i, k] Binomial[i, n - m - k - i])/i!, {i, k, n - m - k}] m^k, {k, 0, n - m}], {n, 9}, {m, n}] // Flatten (* Michael De Vlieger, Jan 15 2016 *)
PROG
(Maxima)
T(n, m):=n!/m!*sum((sum((stirling1(i, k)*binomial(i, n-m-k-i))/i!, i, k, n-m-k))*m^k, k, 0, n-m);
(Sage) # uses[bell_transform from A264428]
# Adds a column 1, 0, 0, 0, ... at the left side of the triangle.
def A202189_row(n):
f = lambda n: factorial(n+1)*sum(sum((-1)^(i-k)*stirling_number1(i, k)* binomial(i, n-k-i)/factorial(i) for i in (k..n-k)) for k in (0..n))
return bell_transform(n, [f(k) for k in (0..n)])
[A202189_row(n) for n in (0..9)] # Peter Luschny, Jan 15 2016
CROSSREFS
Sequence in context: A215080 A317446 A137943 * A202183 A227612 A221273
KEYWORD
sign,tabl,changed
AUTHOR
Vladimir Kruchinin, Dec 13 2011
STATUS
approved