A043956 Numbers k such that 4 and 7 occur juxtaposed in the base-8 representation of k but not of k+1.

39, 60, 103, 124, 167, 188, 231, 252, 295, 319, 359, 380, 423, 444, 487, 508, 551, 572, 615, 636, 679, 700, 743, 764, 807, 831, 871, 892, 935, 956, 999, 1020, 1063, 1084, 1127, 1148, 1191, 1212, 1255, 1276, 1319, 1343, 1383

Offset

1,1

Links

Table of n, a(n) for n=1..43.

Mathematica

Transpose[SequencePosition[Table[If[SequenceCount[IntegerDigits[n, 8], {4, 7}]>0||SequenceCount[IntegerDigits[n, 8], {7, 4}]>0, 1, 0], {n, 1500}], {1, 0}]][[1]] (* The program uses the SequencePosition and SequenceCount functions from Mathematica version 10 *) (* Harvey P. Dale, Jun 08 2016 *)

Crossrefs

Cf. A007094.

Sequence in context: A050780 A039353 A043176 * A090876 A165461 A020166

Adjacent sequences: A043953 A043954 A043955 * A043957 A043958 A043959

Keyword

nonn,base

Author

Clark Kimberling

Status

approved