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A289830 a(n) satisfies the equation n/(n-1) + a(n)/n! = H(n), where H(n) is the n-th harmonic number. 0
-1, 2, 18, 124, 900, 7188, 63504, 618336, 6596640, 76635360, 963895680, 13056819840, 189581333760, 2938083321600, 48416639846400, 845487698227200, 15598004134809600, 303161985274982400, 6191998554470400000, 132599321499875328000, 2970952207377960960000 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,2

LINKS

Table of n, a(n) for n=2..22.

FORMULA

a(n) = n! * (H(n) - n/(n-1)). - Alois P. Heinz, Jul 13 2017

MATHEMATICA

Table[n!*(HarmonicNumber[n] - n/(n - 1)), {n, 2, 22}] (* Michael De Vlieger, Jul 13 2017 *)

PROG

(Python)

from sympy import factorial, harmonic

def a(n): return factorial(n-2)*(harmonic(n)*(n-1) - n)*n

print([a(n) for n in range(2, 26)]) # Indranil Ghosh, Jul 14 2017

CROSSREFS

Cf. A001008, A002805.

Sequence in context: A052610 A052653 A342124 * A060589 A325275 A277661

Adjacent sequences:  A289827 A289828 A289829 * A289831 A289832 A289833

KEYWORD

sign

AUTHOR

Joseph Wheat, Jul 12 2017

EXTENSIONS

More terms from Alois P. Heinz, Jul 13 2017

STATUS

approved

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Last modified August 8 10:26 EDT 2022. Contains 356009 sequences. (Running on oeis4.)