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A126369 Number of base 15 n-digit numbers with adjacent digits differing by one or less. 4
1, 15, 43, 125, 365, 1069, 3137, 9219, 27123, 79869, 235361, 693991, 2047367, 6042659, 17841247, 52694573, 155679885, 460055423, 1359834747, 4020216877, 11887503933, 35156155109, 103985848697, 307611659819, 910083564731 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

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

LINKS

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

FORMULA

G.f.: (1+7*x-57*x^2+73*x^3+75*x^4-121*x^5-33*x^6+37*x^7+4*x^8) / (1-8*x+20*x^2-8*x^3-30*x^4+24*x^5+12*x^6-8*x^7-x^8) (conjectured). - Colin Barker, Jul 18 2017

PROG

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

CROSSREFS

Sequence in context: A173873 A124708 A204734 * A193647 A133343 A027845

Adjacent sequences:  A126366 A126367 A126368 * A126370 A126371 A126372

KEYWORD

nonn,base

AUTHOR

R. H. Hardin, Dec 26 2006

STATUS

approved

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Last modified November 13 08:18 EST 2019. Contains 329093 sequences. (Running on oeis4.)