A126367 Number of base 13 n-digit numbers with adjacent digits differing by one or less.

1, 13, 37, 107, 311, 907, 2651, 7761, 22749, 66747, 195995, 575893, 1693073, 4979777, 14652601, 43128637, 126982109, 373962395, 1101557803, 3245398895, 9563118423, 28183332105, 83068897785, 244867352543, 721877651203

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

Empirical G.f.: -(4*x^7-23*x^6-38*x^5+59*x^4+30*x^3-40*x^2+6*x+1) / ((x-1)*(x^6-6*x^5-13*x^4+8*x^3+8*x^2-6*x+1)). [Colin Barker, Nov 26 2012]

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: A331763 A155263 A155228 * A139926 A155259 A155308

Adjacent sequences: A126364 A126365 A126366 * A126368 A126369 A126370

Keyword

nonn,base

Author

R. H. Hardin, Dec 26 2006

Status

approved