A043254 Numbers k such that 5 and 9 occur juxtaposed in the base-10 representation of k but not of k-1.

59, 95, 159, 195, 259, 295, 359, 395, 459, 495, 559, 590, 659, 695, 759, 795, 859, 895, 950, 995, 1059, 1095, 1159, 1195, 1259, 1295, 1359, 1395, 1459, 1495, 1559, 1590, 1659, 1695, 1759, 1795, 1859, 1895, 1950, 1995, 2059

Offset

1,1

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Maple

N:= 10000: # to get all terms <= N
V:= Vector(N, n -> StringTools:-RegMatch("59|95", convert(n, string))):
select(t -> V[t] and not V[t-1], [$2..N]); # Robert Israel, Dec 11 2015

Mathematica

SequencePosition[Table[If[SequenceCount[IntegerDigits[n], {5, 9}]>0 || SequenceCount[ IntegerDigits[n], {9, 5}]>0, 1, 0], {n, 2500}], {0, 1}][[All, 2]] (* Harvey P. Dale, Jul 20 2022 *)

Crossrefs

Cf. A044034 (similar but with k+1 instead).

Sequence in context: A136076 A186399 A039431 * A044034 A142152 A112804

Adjacent sequences: A043251 A043252 A043253 * A043255 A043256 A043257

Keyword

nonn,base

Author

Clark Kimberling

Status

approved