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A125433
Number of base 21 circular n-digit numbers with adjacent digits differing by 7 or less.
0
1, 21, 259, 2709, 32627, 401401, 5043115, 64108009, 821245795, 10571373945, 136492942139, 1765686281633, 22868116742483, 296391829451401, 3843261172758763, 49848967431027409, 646678407486881219
OFFSET
0,2
COMMENTS
[Empirical] a(base,n)=a(base-1,n)+F(7) for base>=7.int(n/2)+1 and F(d) is the largest coefficient in (1+x+...+x^(2d))^n
PROG
(S/R) stvar $[N]:(0..M-1) init $[]:=0 asgn $[]->{*} kill +[i in 0..N-1](($[i]`-$[(i+1)mod N]`>7)+($[(i+1)mod N]`-$[i]`>7))
CROSSREFS
Sequence in context: A322500 A241632 A323972 * A135122 A231380 A045505
KEYWORD
nonn,base
AUTHOR
R. H. Hardin, Dec 28 2006
STATUS
approved