A383072 - OEIS

A383072

Number of n-digit positive integers where all pairs of consecutive digits have a difference of at least 4.

9, 36, 166, 722, 3224, 14236, 63172, 279728, 1239800, 5492776, 24339328, 107843024, 477848240, 2117296288, 9381580672, 41568964736, 184188672416, 816124473376, 3616179527008, 16022988545120, 70996522976672, 314579653288672, 1393876135246624, 6176148562918496

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OFFSET

1,1

LINKS

Table of n, a(n) for n=1..24.

Index entries for linear recurrences with constant coefficients, signature (3,8,-6,-6).

FORMULA

G.f.: x*(10*x^3+14*x^2-9*x-9)/(-6*x^4-6*x^3+8*x^2+3*x-1). - Alois P. Heinz, Apr 15 2025

MATHEMATICA

LinearRecurrence[{3, 8, -6, -6}, {9, 36, 166, 722}, 24] (* or *) Rest[CoefficientList[Series[x*(10*x^3+14*x^2-9*x-9)/(-6*x^4-6*x^3+8*x^2+3*x-1), {x, 0, 24}] , x]] (* James C. McMahon, Apr 15 2025 *)

CROSSREFS

Cf. A052268, A100062, A383070, A383071.

Sequence in context: A075674 A245416 A265837 * A383354 A264359 A280353

Adjacent sequences: A383069 A383070 A383071 * A383073 A383074 A383075

KEYWORD

nonn,base,easy

AUTHOR

Edwin Hermann, Apr 15 2025

EXTENSIONS

More terms from Alois P. Heinz, Apr 15 2025

STATUS

approved