A080498 - OEIS

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A080498

a(n) = (n-c_1)(n-c_2)...(n-c_k) where c_k is the k-th composite number and is also the largest composite number < n.

1, 1, 1, 1, 1, 2, 3, 8, 15, 48, 210, 1152, 3780, 19200, 62370, 322560, 2162160, 17418240, 81081000, 567705600, 2481078600, 16907304960, 146659312800, 1504935936000, 8799558768000, 76435881984000, 819678899239200

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,6

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..539

EXAMPLE

a(6) = (6-4) = 2. a(10) = (10-4)(10-6)(10-8)(10-9) = 48.

MATHEMATICA

Module[{nn=30, cmps}, cmps=Select[Range[nn], CompositeQ]; Table[Times@@(n-Select[ cmps, #<n&]), {n, nn}]] (* Harvey P. Dale, Aug 13 2024 *)

CROSSREFS

Cf. A080497, A072513, A080500.

Sequence in context: A148012 A161178 A006882 * A148013 A133983 A005162