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A126508 Number of base 13 n-digit numbers with adjacent digits differing by four or less. 1
1, 13, 97, 753, 5897, 46287, 363509, 2855151, 22426249, 176152007, 1383628073, 10868042671, 85365689641, 670525630751, 5266807148873, 41369421713583, 324946216030489, 2552369333410047, 20048207650685929, 157473538310505327 (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+4*x-14*x^2-16*x^3+22*x^4+8*x^5-8*x^6) / (1-9*x+6*x^2+26*x^3-18*x^4-12*x^5+8*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 13 differing by three or less A126481, two or less A126400, one or less A126367.

Sequence in context: A125350 A049294 A198480 * A228680 A158795 A075899

Adjacent sequences:  A126505 A126506 A126507 * A126509 A126510 A126511

KEYWORD

nonn,base

AUTHOR

R. H. Hardin, Dec 28 2006

STATUS

approved

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Last modified January 24 13:24 EST 2020. Contains 331193 sequences. (Running on oeis4.)