A383070 - OEIS

A383070

Number of n-digit positive integers where all pairs of consecutive digits have a difference of at least 2.

9, 64, 463, 3341, 24125, 174172, 1257515, 9079056, 65549673, 473259806, 3416873920, 24669378486, 178109665460, 1285928315349, 9284233050564, 67030939539430, 483954553287069, 3494088121160674, 25226855944238001, 182134576675940879, 1314987650245129696

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OFFSET

1,1

LINKS

Table of n, a(n) for n=1..21.

Index entries for linear recurrences with constant coefficients, signature (4,22,11,-14,-3).

FORMULA

G.f.: x*(3*x^4+18*x^3-9*x^2-28*x-9)/(-3*x^5-14*x^4+11*x^3+22*x^2+4*x-1). - Alois P. Heinz, Apr 15 2025

MATHEMATICA

LinearRecurrence[{4, 22, 11, -14, -3}, {9, 64, 463, 3341, 24125}, 21] (* or *) Rest[CoefficientList[Series[x*(3*x^4+18*x^3-9*x^2-28*x-9)/(-3*x^5-14*x^4+11*x^3+22*x^2+4*x-1), {x, 0, 21}] , x]] (* James C. McMahon, Apr 15 2025 *)

CROSSREFS

Cf. A052268, A100062, A383071, A383072.

Sequence in context: A049684 A037540 A037484 * A378566 A013566 A056769

Adjacent sequences: A383067 A383068 A383069 * A383071 A383072 A383073

KEYWORD

nonn,base,easy

AUTHOR

Edwin Hermann, Apr 15 2025

EXTENSIONS

More terms from Alois P. Heinz, Apr 15 2025

STATUS

approved