login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A141090 Integral quotients of products of first k consecutive composites divided by their sums: products (dividends). 6
4, 1728, 2903040, 12541132800, 115880067072000, 69528040243200000, 1807729046323200000, 43295255277764345856000000, 20188846756043686829592191472500736000000000, 989253491046140654650017382152536064000000000 (list; graph; refs; listen; history; text; internal format)
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: A160225 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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 27 23:01 EDT 2020. Contains 338045 sequences. (Running on oeis4.)