

A093912


Number of terms in nth row of irregular triangle defined in A093911.


1



1, 2, 3, 4, 6, 10, 20, 40, 80, 160, 308, 628, 1256, 2488, 5000, 9940, 19928, 39864, 79660, 159380, 318724, 637496, 1274980, 2549924, 5099884, 10199748, 20399528, 40799020, 81598052, 163196124, 326392240, 652784444, 1305568896, 2611137796
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OFFSET

1,2


COMMENTS

First differences of A093911.


LINKS

Table of n, a(n) for n=1..34.


EXAMPLE

From Michael De Vlieger, Dec 15 2016: (Start)
a(4) = 4 because a(1) is the product of 1 successive numbers starting with 1 = 1, a(2) is the product of 2 successive numbers (2,3) = 6, a(3) is the product of 3 successive numbers (4,5,6) = 120. Finally, a(4) is the product of 4 successive numbers (7,8,9,10) = 5040. All the products have the property that a(n) = 0 (mod a(n  1)). Thus a(4) = 4. (End)


MATHEMATICA

a = {{1, 1}, {2, 2}}; Do[k = Last@ a[[i]]; While[! Divisible[Pochhammer[Total@ a[[i]], k], Pochhammer @@ a[[i]]], k++]; AppendTo[a, {Total@ a[[i]], k}], {i, 2, 16}]; Last /@ a (* Michael De Vlieger, Dec 15 2016 *)


CROSSREFS

Cf. A090906, A093911.
Sequence in context: A056469 A228863 A004047 * A181054 A134696 A151677
Adjacent sequences: A093909 A093910 A093911 * A093913 A093914 A093915


KEYWORD

nonn,easy,less


AUTHOR

Amarnath Murthy, Apr 24 2004


EXTENSIONS

Edited and extended by David Wasserman, Mar 27 2006


STATUS

approved



