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A126511 Number of base 16 n-digit numbers with adjacent digits differing by four or less. 1
1, 16, 124, 996, 8084, 65928, 538668, 4404564, 36026044, 294702188, 2410856988, 19722778372, 161349704452, 1319986934708, 10798704179268, 88343352897012, 722730197415044, 5912600825871716, 48370539666789668, 395715727752799652 (list; graph; refs; listen; history; text; internal format)
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.

LINKS

Table of n, a(n) for n=0..19.

FORMULA

G.f.: (1+7*x-20*x^2-70*x^3-40*x^4+8*x^5+6*x^6) / (1-9*x+50*x^3+40*x^4-4*x^5-6*x^6) (conjectured). - Colin Barker, Jul 18 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 16 differing by three or less A126484, two or less A126403, one or less A126370.

Sequence in context: A227088 A060633 A125353 * A231582 A067442 A000485

Adjacent sequences:  A126508 A126509 A126510 * A126512 A126513 A126514

KEYWORD

nonn,base

AUTHOR

R. H. Hardin, Dec 28 2006

STATUS

approved

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Last modified October 14 11:55 EDT 2019. Contains 327999 sequences. (Running on oeis4.)