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A043230
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Numbers k such that 1 and 7 occur juxtaposed in the base-10 representation of k but not of k-1.
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0
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17, 71, 117, 170, 217, 271, 317, 371, 417, 471, 517, 571, 617, 671, 710, 771, 817, 871, 917, 971, 1017, 1071, 1117, 1170, 1217, 1271, 1317, 1371, 1417, 1471, 1517, 1571, 1617, 1671, 1700, 1817, 1871, 1917, 1971, 2017, 2071
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OFFSET
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1,1
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LINKS
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MATHEMATICA
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SequencePosition[Table[If[SequenceCount[IntegerDigits[n], {1, 7}]>0 || SequenceCount[IntegerDigits[n], {7, 1}]>0, 1, 0], {n, 2100}], {0, 1}][[All, 2]] (* Harvey P. Dale, Oct 17 2021 *)
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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