A043208 Numbers k such that 4 and 7 occur juxtaposed in the base-9 representation of k but not of k-1.

43, 67, 124, 148, 205, 229, 286, 310, 367, 387, 448, 472, 529, 553, 603, 634, 691, 715, 772, 796, 853, 877, 934, 958, 1015, 1039, 1096, 1116, 1177, 1201, 1258, 1282, 1332, 1363, 1420, 1444, 1501, 1525, 1582, 1606, 1663, 1687

Offset

1,1

Links

Table of n, a(n) for n=1..42.

Mathematica

SequencePosition[Table[If[SequenceCount[IntegerDigits[n, 9], {4, 7}]>0 || SequenceCount[IntegerDigits[n, 9], {7, 4}]>0, 1, 0], {n, 2000}], {0, 1}][[All, 2]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jul 28 2018 *)

Crossrefs

Cf. A007095.

Sequence in context: A139917 A146334 A039385 * A043988 A139499 A201688

Adjacent sequences: A043205 A043206 A043207 * A043209 A043210 A043211

Keyword

nonn,base

Author

Clark Kimberling

Status

approved