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A043234
Numbers k such that 2 and 4 occur juxtaposed in the base-10 representation of k but not of k-1.
0
24, 42, 124, 142, 224, 240, 324, 342, 420, 442, 524, 542, 624, 642, 724, 742, 824, 842, 924, 942, 1024, 1042, 1124, 1142, 1224, 1240, 1324, 1342, 1420, 1442, 1524, 1542, 1624, 1642, 1724, 1742, 1824, 1842, 1924, 1942, 2024
OFFSET
1,1
MATHEMATICA
SequencePosition[Table[If[SequenceCount[IntegerDigits[n], {2, 4}]>0||SequenceCount[ IntegerDigits[ n], {4, 2}]>0, 1, 0], {n, 2500}], {0, 1}][[;; , 2]] (* Harvey P. Dale, Sep 15 2024 *)
CROSSREFS
Sequence in context: A228844 A111948 A039411 * A044014 A087093 A118299
KEYWORD
nonn,base
STATUS
approved