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A126373 Number of base 19 n-digit numbers with adjacent digits differing by one or less. 4
1, 19, 55, 161, 473, 1393, 4109, 12135, 35871, 106113, 314093, 930187, 2755955, 8168423, 24218539, 71826449, 213075513, 632242305, 1876395357, 5569898331, 16536545331, 49103259773, 145827049265, 433134662087, 1286649627671 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

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

LINKS

Table of n, a(n) for n=0..24.

FORMULA

G.f.: (1+9*x-100*x^2+236*x^3-7*x^4-469*x^5+216*x^6+290*x^7-111*x^8-53*x^9+6*x^10) / ((1-2*x-x^2)*(1-8*x+20*x^2-8*x^3-31*x^4+28*x^5+10*x^6-12*x^7+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]`-$[i+1]`>1)+($[i+1]`-$[i]`>1))

CROSSREFS

Sequence in context: A044502 A069131 A124712 * A125818 A093362 A251073

Adjacent sequences:  A126370 A126371 A126372 * A126374 A126375 A126376

KEYWORD

nonn,base

AUTHOR

R. H. Hardin, Dec 26 2006

STATUS

approved

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Last modified October 15 17:24 EDT 2019. Contains 328037 sequences. (Running on oeis4.)