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 A056923 Write the integers in groups: 0; 1,2; 3,4,5; 6,7,8,9; ... and form the product of the members of each group. 0
 0, 2, 60, 3024, 240240, 27907200, 4475671200, 948964262400, 257256702743040, 86839771951296000, 35728290125079552000, 17602963463032472448000, 10233395250958706770944000, 6932022668773077815267328000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Each group begins with a triangular number and proceeds until one short of the next triangular number. Also, the number under the radical using Brahmagupta's formula for a n-sided cyclic quadrilateral with sides 1..n - Ben Thurston (benthurston27(AT)yahoo.com), Dec 05 2006 LINKS Nick's Mathematical Puzzles, Problem p10 FORMULA (n (n + 3)/2)!/((n - 1)(n + 2)/2)! (s-1)*(s-2)*...*(s-n) where s is the sum(n, n=0..i) - Ben Thurston (benthurston27(AT)yahoo.com), Dec 05 2006 MAPLE m:=1; for i from 1 to 10 do m:=1; for j from 1 to i do m:= m*(sum(k, k = 0..i)-j); end do; print(m); end do; - Ben Thurston (benthurston27(AT)yahoo.com), Dec 05 2006 MATHEMATICA Table[(n (n + 3)/2)!/((n - 1)(n + 2)/2)!, {n, 0, 15}] CROSSREFS Cf. A027480. Sequence in context: A157059 A222652 A199643 * A173221 A082787 A078423 Adjacent sequences:  A056920 A056921 A056922 * A056924 A056925 A056926 KEYWORD nonn AUTHOR Robert G. Wilson v, Sep 09 2000 STATUS approved

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