A124726 Number of base 27 circular n-digit numbers with adjacent digits differing by 1 or less.

1, 27, 79, 183, 491, 1307, 3583, 9911, 27715, 78051, 221159, 629711, 1800371, 5165187, 14862871, 42878543, 123982195, 359207987, 1042568407, 3030781151, 8823230131, 25719643811, 75061264951, 219298798031, 641338650427

Offset: 0

Author

R. H. Hardin, Dec 28 2006

Keywords

• nonn
• base

Comments

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

a(n) = T(n, 27) 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,..,27}. See theorem 3.3 in Knopfmacher and others, reference in A124696. - Peter Luschny, Aug 13 2012

Links

• OEIS Wiki, Number of base k circular n-digit numbers with adjacent digits differing by d or less

Extensions

Edited by Charles R Greathouse IV, Aug 05 2010