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A091551
Second column (k=3) sequence of array ((7,2)-Stirling2) divided by 14.
1
1, 228, 83232, 46854720, 38109367296, 42479241412608, 62290218157719552, 116373513947009679360, 270010358636135897235456, 762020881523854021734432768, 2571195906705444158241905836032
OFFSET
0,2
FORMULA
a(n)= product(5*j+2, j=0..n-1)*(-3*product(5*j+1, j=0..n-1) + product(5*j+3, j=0..n-1))/(3!*14), n>=2. From eq.12 of the Blasiak et al. reference given in A007840 with r=7, s=2, k=3.
a(n)= (5^(2*n))*risefac(2/5, n)*(-3*risefac(1/5, n) + risefac(3/5, n))/(3!*14), n>=2, with risefac(x, n)=Pochhammer(x, n).
E.g.f.: (hypergeom([2/5, 3/5], [], 25*x) - 3*hypergeom([1/5, 2/5], [], 25*x) + 2)/(3!*14).
CROSSREFS
Cf. A091550 (second column of (6, 2)-Stirling2 array), A091552 (second column of (8, 2)-Stirling2 array).
Sequence in context: A201238 A220624 A098246 * A033528 A086002 A061783
KEYWORD
nonn,easy
AUTHOR
Wolfdieter Lang, Feb 13 2004
STATUS
approved