A125409 Number of base 21 circular n-digit numbers with adjacent digits differing by 6 or less.

1, 21, 231, 2121, 22547, 244601, 2714271, 30517333, 346395491, 3958011609, 45437784111, 523343937005, 6041702589491, 69860441606457, 808706293207743, 9368913912846221, 108598284502838979, 1259272889680954201

Offset

0,2

Comments

[Empirical] a(base,n)=a(base-1,n)+F(6) for base>=6.int(n/2)+1 and F(d) is the largest coefficient in (1+x+...+x^(2d))^n

Links

Table of n, a(n) for n=0..17.

Prog

(S/R) stvar $[N]:(0..M-1) init $[]:=0 asgn $[]->{*} kill +[i in 0..N-1](($[i]`-$[(i+1)mod N]`>6)+($[(i+1)mod N]`-$[i]`>6))

Crossrefs

Sequence in context: A010973 A022586 A321952 * A161581 A350570 A069601

Adjacent sequences: A125406 A125407 A125408 * A125410 A125411 A125412

Keyword

nonn,base

Author

R. H. Hardin, Dec 28 2006

Status

approved