A126521 Number of base 26 n-digit numbers with adjacent digits differing by four or less.

1, 26, 214, 1806, 15374, 131538, 1128990, 9710910, 83652388, 721363974, 6225222156, 53750847042, 464278918952, 4011329573242, 34664086928592, 299591386800116, 2589524785835700, 22384118655449566, 193499832018326518

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 26 differing by three or less A126494, two or less A126413, one or less A126380.

Sequence in context: A042310 A213123 A125363 * A242262 A241938 A317865

Adjacent sequences: A126518 A126519 A126520 * A126522 A126523 A126524

Keyword

nonn,base

Author

R. H. Hardin, Dec 28 2006

Status

approved