[seqfan] Trivial array of powers

Richard J. Mathar mathar at mpia-hd.mpg.de
Wed Dec 9 11:05:35 CET 2015


Here is a another boring array apparently well hidden in the OEIS:

      1       2       3       4       5       6       7       8 
      0       2       6      12      20      30      42      56 
      0       2      12      36      80     150     252     392 
      0       2      24     108     320     750    1512    2744 
      0       2      48     324    1280    3750    9072   19208 
      0       2      96     972    5120   18750   54432  134456 
      0       2     192    2916   20480   93750  326592  941192 
      0       2     384    8748   81920  468750 1959552 6588344 

defined by T(n,l)= l*(l-1)^(n-1), giving the number of n-letter
words drawn from an alphabet of l letters, and no adjacent letters the same.
Rows n>=1. Columns l>=1. Closely related to A051129.
(Actualy: the aray of n-leter words; "let(t)er" and "ar(r)ay" are not in the
dictionary admit(t)ed by this definition.)

Richard


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