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A044017
Numbers k such that 2 and 7 occur juxtaposed in the base-10 representation of k but not of k+1.
0
27, 72, 127, 172, 227, 279, 327, 372, 427, 472, 527, 572, 627, 672, 729, 772, 827, 872, 927, 972, 1027, 1072, 1127, 1172, 1227, 1279, 1327, 1372, 1427, 1472, 1527, 1572, 1627, 1672, 1729, 1772, 1827, 1872, 1927, 1972, 2027
OFFSET
1,1
MATHEMATICA
Transpose[SequencePosition[Table[If[SequenceCount[IntegerDigits[n], {2, 7}]>0||SequenceCount[IntegerDigits[n], {7, 2}]>0, 1, 0], {n, 2100}], {1, 0}]][[1]] (* The program uses the SequencePosition and SequenceCount functions from Mathematica version 10 *) (* Harvey P. Dale, May 23 2015 *)
CROSSREFS
Sequence in context: A181976 A039414 A043237 * A147651 A325824 A163506
KEYWORD
nonn,base
STATUS
approved