A141090 Integral quotients of products of first k consecutive composites divided by their sums: products (dividends).

4, 1728, 2903040, 12541132800, 115880067072000, 69528040243200000, 1807729046323200000, 43295255277764345856000000, 20188846756043686829592191472500736000000000, 989253491046140654650017382152536064000000000

Offset

1,1

Comments

Based on A141092.

Compare with A140761 A159578 A140763 A116536.

Take the first k composite numbers. If their product divided by their sum results in an integer, their product is a term of the sequence. - Harvey P. Dale, Apr 29 2018

Links

Amiram Eldar, Table of n, a(n) for n = 1..93

Formula

Find the products and sums of first k consecutive composites. When the product divided by the sum produces an integral quotient, add product to sequence.

Example

a(3) = 2903040 because 4*6*8*9*10*12*14 = 2903040 and 4+6+8+9+10+12+14 = 63; 2903040/63 = 46080, integral -- 2903040 is added to the sequence.

Mathematica

With[{c=Select[Range[100], CompositeQ]}, Table[If[IntegerQ[ Times@@Take[ c, n]/Total[ Take[ c, n]]], Times@@ Take[ c, n], 0], {n, Length[c]}]]/.(0-> Nothing) (* Harvey P. Dale, Apr 29 2018 *)

Crossrefs

Cf. A196415, A141089, A141091, A141092.

Sequence in context: A377601 A316484 A278794 * A307580 A255268 A079402

Adjacent sequences: A141087 A141088 A141089 * A141091 A141092 A141093

Keyword

easy,nonn

Author

Enoch Haga, Jun 01 2008

Extensions

Checked by N. J. A. Sloane, Oct 02 2011

Edited by N. J. A. Sloane, Apr 29 2018

Status

approved