A126511 Number of base 16 n-digit numbers with adjacent digits differing by four or less.

1, 16, 124, 996, 8084, 65928, 538668, 4404564, 36026044, 294702188, 2410856988, 19722778372, 161349704452, 1319986934708, 10798704179268, 88343352897012, 722730197415044, 5912600825871716, 48370539666789668, 395715727752799652

Offset

0,2

Comments

[Empirical] a(base,n)=a(base-1,n)+9^(n-1) for base>=4n-3; a(base,n)=a(base-1,n)+9^(n-1)-2 when base=4n-4.

Links

Table of n, a(n) for n=0..19.

Formula

G.f.: (1+7*x-20*x^2-70*x^3-40*x^4+8*x^5+6*x^6) / (1-9*x+50*x^3+40*x^4-4*x^5-6*x^6) (conjectured). - Colin Barker, Jul 18 2017

Prog

(S/R) stvar $[N]:(0..M-1) init $[]:=0 asgn $[]->{*} kill +[i in 0..N-2](($[i]`-$[i+1]`>4)+($[i+1]`-$[i]`>4))

Crossrefs

Cf. Base 16 differing by three or less A126484, two or less A126403, one or less A126370.

Sequence in context: A227088 A060633 A125353 * A231582 A067442 A000485

Adjacent sequences: A126508 A126509 A126510 * A126512 A126513 A126514

Keyword

nonn,base

Author

R. H. Hardin, Dec 28 2006

Status

approved