A044804 Numbers m such that string 9,1 occurs in the base 10 representation of m but not of m+1.

91, 191, 291, 391, 491, 591, 691, 791, 891, 919, 991, 1091, 1191, 1291, 1391, 1491, 1591, 1691, 1791, 1891, 1919, 1991, 2091, 2191, 2291, 2391, 2491, 2591, 2691, 2791, 2891, 2919, 2991, 3091, 3191, 3291, 3391, 3491, 3591, 3691, 3791, 3891, 3919, 3991, 4091, 4191

Offset

1,1

Links

Table of n, a(n) for n=1..46.

Mathematica

SequencePosition[Table[If[SequenceCount[IntegerDigits[n], {9, 1}]>0, 1, 0], {n, 4000}], {1, 0}][[All, 1]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Dec 14 2019 *)

Prog

(PARI) isok(m) = (#strsplit(Str(m), "91") > 1) && (#strsplit(Str(m+1), "91") == 1); \\ Michel Marcus, Feb 18 2021

Crossrefs

Sequence in context: A064904 A352133 A044423 * A211443 A305761 A339523

Adjacent sequences: A044801 A044802 A044803 * A044805 A044806 A044807

Keyword

nonn,base

Author

Clark Kimberling

Extensions

Conjecture on linear recurrence removed by Georg Fischer, Feb 18 2021

Status

approved