A126513 Number of base 18 n-digit numbers with adjacent digits differing by four or less.

1, 18, 142, 1158, 9542, 79050, 656612, 5461074, 45448824, 378357098, 3150263772, 26231558496, 218432355062, 1818936380306, 15146831517282, 126132762778328, 1050352117472084, 8746662279539970, 72836658556602482

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..18.

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 18 differing by three or less A126486, two or less A126405, one or less A126372.

Sequence in context: A125355 A299834 A231951 * A232820 A143992 A127408

Adjacent sequences: A126510 A126511 A126512 * A126514 A126515 A126516

Keyword

nonn,base

Author

R. H. Hardin, Dec 28 2006

Status

approved