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A126408 Number of base 21 n-digit numbers with adjacent digits differing by two or less. 3
1, 21, 99, 475, 2293, 11111, 53973, 262649, 1279855, 6243155, 30479985, 148910385, 727918557, 3559976043, 17417455619, 85244931269, 417326666085, 2043565752795, 10008988327829, 49030629716903, 240219997723397 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

[Empirical] a(base,n)=a(base-1,n)+5^(n-1) for base>=2n-1; a(base,n)=a(base-1,n)+5^(n-1)-2 when base=2n-2

LINKS

Table of n, a(n) for n=0..20.

PROG

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

CROSSREFS

Cf. Base 21 differing by one or less A126375.

Sequence in context: A140370 A124949 A267681 * A174080 A157329 A044272

Adjacent sequences:  A126405 A126406 A126407 * A126409 A126410 A126411

KEYWORD

nonn,base

AUTHOR

R. H. Hardin, Dec 28 2006

STATUS

approved

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Last modified August 10 04:38 EDT 2020. Contains 336368 sequences. (Running on oeis4.)