login
This site is supported by donations to The OEIS Foundation.

 

Logo

Annual appeal: Please make a donation to keep the OEIS running! Over 6000 articles have referenced us, often saying "we discovered this result with the help of the OEIS".
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A126475 Number of base 7 n-digit numbers with adjacent digits differing by three or less. 3
1, 7, 37, 203, 1111, 6083, 33305, 182349, 998383, 5466269, 29928491, 163862147, 897165287, 4912089625, 26894291201, 147249532159, 806209189861, 4414093873755, 24167703582839, 132321131623579, 724474371929041 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

[Empirical] a(base,n)=a(base-1,n)+7^(n-1) for base>=3n-2; a(base,n)=a(base-1,n)+7^(n-1)-2 when base=3n-3.

LINKS

Table of n, a(n) for n=0..20.

FORMULA

Conjectures from Colin Barker, Jun 01 2017: (Start)

G.f.: (1 + 2*x - x^2 - x^3) / (1 - 5*x - 3*x^2 + 2*x^3 + x^4).

a(n) = 5*a(n-1) + 3*a(n-2) - 2*a(n-3) - a(n-4) for n>3.

(End)

PROG

(S/R) stvar $[N]:(0..M-1) init $[]:=0 asgn $[]->{*} kill +[i in 0..N-2](($[i]`-$[i+1]`>3)+($[i+1]`-$[i]`>3))

CROSSREFS

Cf. Base 7 differing by two or less A126394, one or less A126361.

Sequence in context: A002807 A124610 A002683 * A274674 A255672 A077239

Adjacent sequences:  A126472 A126473 A126474 * A126476 A126477 A126478

KEYWORD

nonn,base

AUTHOR

R. H. Hardin, Dec 27 2006

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified November 23 00:33 EST 2017. Contains 295107 sequences.