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A123931 a(n) = H(n)*n!/(floor(n/2))! (mod (n+1)), where H(n) = sum{k=1 to n} 1/k, the n-th harmonic number. 1
0, 1, 0, 3, 0, 5, 0, 2, 3, 4, 0, 0, 0, 6, 9, 0, 0, 0, 0, 0, 18, 10, 0, 0, 0, 12, 0, 0, 0, 0, 0, 0, 30, 16, 0, 0, 0, 18, 24, 0, 0, 0, 0, 0, 0, 22, 0, 0, 0, 0, 12, 0, 0, 0, 0, 0, 54, 28, 0, 0, 0, 30, 0, 0, 0, 0, 0, 0, 3, 0, 0, 0, 0, 36, 0, 0, 0, 0, 0, 0, 0, 40, 0, 0, 0, 42, 51, 0, 0, 0, 0, 0, 3, 46, 0, 0, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,4
LINKS
MATHEMATICA
f[n_]:= Mod[HarmonicNumber[n]n!/Floor[n/2]!, n + 1]; Table[f[n], {n, 0, 100}] (* Ray Chandler, Dec 11 2006 *)
PROG
(PARI) a(n) = (n!*sum(k=1, n, 1/k)/(n\2)!)%(n+1);
vector(100, n, n--; a(n) ) \\ G. C. Greubel, Aug 05 2019
(Sage) [mod(harmonic_number(n)*factorial(n)/factorial(floor(n/2)), n+1) for n in (0..100)] # G. C. Greubel, Aug 05 2019
(GAP)List([0..100], n-> (Factorial(n)*Sum([1..n], k-> 1/k)/Factorial(Int(n/2))) mod (n+1) ); # G. C. Greubel, Aug 05 2019
CROSSREFS
Cf. A124078.
Sequence in context: A122274 A340525 A003966 * A058026 A004605 A369700
KEYWORD
easy,nonn
AUTHOR
Leroy Quet, Nov 28 2006
EXTENSIONS
Extended by Ray Chandler, Dec 11 2006
STATUS
approved

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Last modified March 19 07:36 EDT 2024. Contains 370956 sequences. (Running on oeis4.)