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A126507
Number of base 12 n-digit numbers with adjacent digits differing by four or less.
1
1, 12, 88, 672, 5168, 39796, 306520, 2361008, 18186104, 140082072, 1079010248, 8311293248, 64019406944, 493122351856, 3798374049312, 29257739717488, 225363621979872, 1735908604096736, 13371185000068864, 102994240528644064
OFFSET
0,2
COMMENTS
[Empirical] a(base,n)=a(base-1,n)+9^(n-1) for base>=4n-3; a(base,n)=a(base-1,n)+9^(n-1)-2 when base=4n-4.
FORMULA
G.f.: (1+4*x-8*x^2-14*x^3+6*x^4+6*x^5) / (1-8*x+18*x^3-2*x^4-6*x^5) (conjectured). - Colin Barker, Jul 17 2017
PROG
(S/R) stvar $[N]:(0..M-1) init $[]:=0 asgn $[]->{*} kill +[i in 0..N-2](($[i]`-$[i+1]`>4)+($[i+1]`-$[i]`>4))
CROSSREFS
Cf. Base 12 differing by three or less A126480, two or less A126399, one or less A126366.
Sequence in context: A164608 A081009 A155635 * A181704 A009657 A012088
KEYWORD
nonn,base
AUTHOR
R. H. Hardin, Dec 28 2006
STATUS
approved