A126526 Number of base 31 n-digit numbers with adjacent digits differing by four or less.

1, 31, 259, 2211, 19019, 164343, 1424235, 12368115, 107567215, 936593437, 8162112673, 71178552195, 621048996119, 5421039243545, 47334756754423, 413416811445643, 3611458265770503, 31553302705135081, 275714829055325817

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 31 differing by three or less A126499, two or less A126418, one or less A126385.

Sequence in context: A089705 A180471 A125368 * A008386 A161558 A336279

Adjacent sequences: A126523 A126524 A126525 * A126527 A126528 A126529

Keyword

nonn,base

Author

R. H. Hardin, Dec 28 2006

Status

approved