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A203417 A203415(n)/A000178(n). 5
1, 3, 15, 140, 700, 2520, 44352, 2196480, 47567520, 634233600, 51753461760, 13984935444480, 1448751906201600, 82605199597240320, 32797812715211980800, 5296846753506734899200, 483765735240908144640000, 28985693293514522492928000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..18.

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

Index to divisibility sequences

MATHEMATICA

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

nonprime = Rest[Union[t]];

f[j_] := nonprime[[j]]; z = 20;  (* A018252 *)

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}]              (* A203415 *)

Table[v[n + 1]/v[n], {n, 1, z - 1}] (* A203416 *)

Table[v[n]/d[n], {n, 1, 20}]        (* A203417 *)

CROSSREFS

Cf. A203415, A203416, A000040, A018252.

Sequence in context: A179470 A270524 A179471 * A086228 A288456 A230367

Adjacent sequences:  A203414 A203415 A203416 * A203418 A203419 A203420

KEYWORD

nonn

AUTHOR

Clark Kimberling, Jan 01 2012

STATUS

approved

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Last modified June 16 13:34 EDT 2019. Contains 324152 sequences. (Running on oeis4.)