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A203420 a(n) = A203418(n)/A000178(n) where A000178=(superfactorials). 4
1, 2, 8, 20, 40, 384, 10240, 126720, 1013760, 48660480, 7612661760, 473174507520, 16701626253312, 4036421002199040, 407426244909465600, 23814785343474892800, 932976775107465707520, 26694111965427724713984, 9044593230639040844267520 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..19.

R. Chapman, A polynomial taking integer values, Mathematics Magazine, 29 (1996), 121.

MATHEMATICA

t = Table[If[PrimeQ[k], 0, k], {k, 1, 100}];

composite = Rest[Rest[Union[t]]] (* A002808 *)

f[j_] := composite[[j]]; z = 20 ;

v[n_] := Product[Product[f[k] - f[j], {j, 1, k - 1}], {k, 2, n}]

d[n_] := Product[(i - 1)!, {i, 1, n}]

Table[v[n], {n, 1, z}]              (* A203418 *)

Table[v[n + 1]/v[n], {n, 1, z - 1}] (* A203419 *)

Table[v[n]/d[n], {n, 1, 20}]        (* A203420 *)

CROSSREFS

Cf. A202808, A203418, A000040, A018252, A203417.

Sequence in context: A007290 A049031 A058037 * A048096 A072250 A220908

Adjacent sequences:  A203417 A203418 A203419 * A203421 A203422 A203423

KEYWORD

nonn

AUTHOR

Clark Kimberling, Jan 02 2012

STATUS

approved

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Last modified May 29 15:44 EDT 2020. Contains 334704 sequences. (Running on oeis4.)