

A125370


Number of base 7 circular ndigit numbers with adjacent digits differing by 5 or less.


0



1, 7, 47, 307, 2067, 13927, 93887, 632947, 4267107, 28767367, 193939727, 1307475187, 8814549747, 59424674407, 400620795167, 2700848143027, 18208192833987, 122753397719047, 827561350484207, 5579135091500467
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OFFSET

0,2


COMMENTS

[Empirical] a(base,n)=a(base1,n)+F(5) for base>=5.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..19.


FORMULA

Conjectures from Colin Barker, Jun 02 2017: (Start)
G.f.: (1  x^2  10*x^3) / ((1  x)*(1  6*x  5*x^2)).
a(n) = 1 + (3sqrt(14))^n + (3+sqrt(14))^n for n>0.
a(n) = 7*a(n1)  a(n2)  5*a(n3) for n>3.
(End)


PROG

(S/R) stvar $[N]:(0..M1) init $[]:=0 asgn $[]>{*} kill +[i in 0..N1](($[i]`$[(i+1)mod N]`>5)+($[(i+1)mod N]`$[i]`>5))


CROSSREFS

Sequence in context: A229010 A126635 A085352 * A163346 A186446 A244830
Adjacent sequences: A125367 A125368 A125369 * A125371 A125372 A125373


KEYWORD

nonn,base


AUTHOR

R. H. Hardin, Dec 28 2006


STATUS

approved



