A093910 Product of n-th row of irregular triangle defined in A093911.

1, 6, 120, 5040, 5765760, 19275223968000, 13644281345408020027550269440000, 4402827357584746886229433170489943024971625310770489684257669120000000000

Offset

1,2

Comments

Next term has 168 digits.

Links

Michael De Vlieger, Table of n, a(n) for n = 1..11 (Term 11 has 824 decimal digits.)

Formula

For n > 1, a(n) = prod_{i = A093911(n)..A093911(n+1)-1} i.

Example

a(3) = 120 because a(1) is the product of 1 successive numbers starting with 1 = 1, and a(2) is the product of 2 successive numbers (2,3) = 6 and a(3) is the product of 3 successive numbers (4,5,6) = 120. All the products have the property that a(n) = 0 (mod a(n - 1)). Thus a(3) = 120.

Mathematica

a = {{1, 1}, {2, 2}}; Do[k = Last@ a[[i - 1]]; While[! Divisible[Pochhammer[Total@ a[[i - 1]], k], Pochhammer @@ a[[i - 1]]], k++]; AppendTo[a, {Total@ a[[i - 1]], k}], {i, 3, 8}]; Pochhammer @@ # & /@ a (* Michael De Vlieger, Dec 15 2016 *)

Crossrefs

Cf. A090904, A093911.

Sequence in context: A094273 A335334 A094278 * A002370 A012846 A331640

Adjacent sequences: A093907 A093908 A093909 * A093911 A093912 A093913

Keyword

nonn,easy,less

Author

Amarnath Murthy, Apr 24 2004

Extensions

Edited and extended by David Wasserman, Mar 27 2006

New name from Ivan Neretin, Dec 15 2016

Status

approved