A247947 Four-digit odd semiprimes with all digits distinct.

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

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