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A126486 Number of base 18 n-digit numbers with adjacent digits differing by three or less. 2
1, 18, 114, 742, 4874, 32186, 213226, 1415510, 9409592, 62605198, 416772336, 2775553058, 18488673878, 123177305178, 820730049614, 5468888194572, 36443213300730, 242854735692378, 1618394841578240, 10785184848010492 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

[Empirical] a(base,n)=a(base-1,n)+7^(n-1) for base>=3n-2; a(base,n)=a(base-1,n)+7^(n-1)-2 when base=3n-3.

LINKS

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

FORMULA

G.f.: (1+7*x-58*x^2-12*x^3+169*x^4-3*x^5-128*x^6+3*x^7+24*x^8) / (1-11*x+26*x^2+32*x^3-83*x^4-21*x^5+64*x^6+3*x^7-12*x^8) (conjectured). - Colin Barker, Jul 18 2017

PROG

(S/R) stvar $[N]:(0..M-1) init $[]:=0 asgn $[]->{*} kill +[i in 0..N-2](($[i]`-$[i+1]`>3)+($[i+1]`-$[i]`>3))

CROSSREFS

Cf. Base 18 differing by two or less A126405, one or less A126372.

Sequence in context: A324623 A244866 A125328 * A251937 A061803 A207103

Adjacent sequences: A126483 A126484 A126485 * A126487 A126488 A126489

KEYWORD

nonn,base

AUTHOR

R. H. Hardin, Dec 27 2006

STATUS

approved

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Last modified January 28 08:35 EST 2023. Contains 359850 sequences. (Running on oeis4.)