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A247947 Four-digit odd semiprimes with all digits distinct. 3
1027, 1037, 1043, 1047, 1057, 1059, 1067, 1073, 1079, 1203, 1205, 1207, 1243, 1247, 1253, 1257, 1263, 1267, 1273, 1285, 1293, 1329, 1345, 1347, 1349, 1357, 1369, 1379, 1385, 1387, 1389, 1397, 1403, 1405, 1437, 1457, 1465, 1469, 1473, 1497, 1507, 1509, 1527, 1529 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

There are exactly 863 four-digit odd semiprimes with all distinct digits. The last few terms of the sequence are: 9563, 9571, 9573, 9607, 9617, 9627, 9637, 9641, 9647, 9651, 9671, 9673, 9683, 9687, 9701, 9703, 9713, 9731, 9745, 9753, 9761, 9763, 9813, 9827, 9841, 9847, 9853, 9863, 9865.

See the link with the b-file for all 863 entries.

LINKS

K. D. Bajpai, Table of n, a(n) for n = 1..863

EXAMPLE

a(1) = 1027 = 13 * 79 is the smallest four-digit odd semiprime with all digits distinct.

a(863) = 9865 = 5 * 1973 is the largest four-digit odd semiprime with all digits distinct.

MATHEMATICA

c = 0; Do[If[Length[Union[IntegerDigits[n]]] == 4 && PrimeOmega[n] == 2, c++; Print[c, "  ", n]], {n, 1001, 9999, 2}]

CROSSREFS

Cf. A001358, A046315, A074673, A235690.

Sequence in context: A168153 A246245 A235692 * A066133 A119455 A252772

Adjacent sequences:  A247944 A247945 A247946 * A247948 A247949 A247950

KEYWORD

nonn,base,fini,full

AUTHOR

K. D. Bajpai, Sep 27 2014

STATUS

approved

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Last modified August 26 00:35 EDT 2019. Contains 326324 sequences. (Running on oeis4.)