A043243 Numbers k such that 3 and 7 occur juxtaposed in the base-10 representation of k but not of k-1.

37, 73, 137, 173, 237, 273, 337, 370, 437, 473, 537, 573, 637, 673, 730, 773, 837, 873, 937, 973, 1037, 1073, 1137, 1173, 1237, 1273, 1337, 1370, 1437, 1473, 1537, 1573, 1637, 1673, 1730, 1773, 1837, 1873, 1937, 1973, 2037

Offset

1,1

Links

Table of n, a(n) for n=1..41.

Mathematica

SequencePosition[Table[If[SequenceCount[IntegerDigits[n], {3, 7}]>0|| SequenceCount[ IntegerDigits[n], {7, 3}]>0, 1, 0], {n, 2100}], {0, 1}][[All, 2]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jul 29 2018 *)

Crossrefs

Sequence in context: A055604 A135952 A039420 * A044023 A179579 A069204

Adjacent sequences: A043240 A043241 A043242 * A043244 A043245 A043246

Keyword

nonn,base

Author

Clark Kimberling

Status

approved