A124715 Number of base 22 circular n-digit numbers with adjacent digits differing by 1 or less.

1, 22, 64, 148, 396, 1052, 2878, 7946, 22180, 62356, 176394, 501446, 1431426, 4100482, 11781736, 33940508, 97999060, 283533332, 821804362, 2385796886, 6936333286, 20192890166, 58855587316, 171732657416, 501596968522

Offset

0,2

Comments

[Empirical] a(base,n)=a(base-1,n)+A002426(n+1) for base>=1.int(n/2)+1

a(n) = T(n, 22) where T(n, k) = Sum_{j=1..k} (1+2*cos(j*Pi/(k+1)))^n. These are the number of smooth cyclic words of length n over the alphabet {1,2,..,22}. See theorem 3.3 in Knopfmacher and others, reference in A124696. - Peter Luschny, Aug 13 2012

Links

Table of n, a(n) for n=0..24.

Prog

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

Crossrefs

Sequence in context: A069178 A081929 A305064 * A126376 A136604 A064710

Adjacent sequences: A124712 A124713 A124714 * A124716 A124717 A124718

Keyword

nonn,base

Author

R. H. Hardin, Dec 28 2006

Status

approved