A093911 Left side of irregular triangle of natural numbers in which the n-th row has at least n terms and every row product is a multiple of the previous.
1, 2, 4, 7, 11, 17, 27, 47, 87, 167, 327, 635, 1263, 2519, 5007, 10007, 19947, 39875, 79739, 159399, 318779, 637503, 1274999, 2549979, 5099903, 10199787, 20399535, 40799063, 81598083, 163196135, 326392259, 652784499, 1305568943, 2611137839
Offset: 1
Examples
The first 5 groups are (1), (2,3), (4,5,6), (7,8,9,10), (11,12,13,14,15,16). The 5th group ends with 16 because 11*12*13*14*15*16 is divisible by 7*8*9*10, but 11*12*13*14*15 is not.
Programs
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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 *)
Extensions
Edited and extended by David Wasserman, Mar 27 2006
Comments