A290752 Semiprimes beginning with 1 such that deleting the 1 leaves a prime.

15, 111, 119, 123, 129, 141, 143, 159, 161, 183, 1003, 1007, 1011, 1037, 1041, 1043, 1047, 1059, 1067, 1073, 1079, 1101, 1137, 1139, 1149, 1157, 1167, 1191, 1199, 1211, 1227, 1241, 1257, 1263, 1271, 1293, 1313, 1317, 1337, 1347, 1349, 1379, 1383, 1389, 1397, 1401, 1457, 1461, 1509, 1541, 1563

Offset

1,1

Comments

After deleting the 1, leading zeros are allowed (see also A290753).

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Maple

filter:= n -> numtheory:-bigomega(n) = 2 and isprime(n - 10^ilog10(n)):
select(filter, [seq(seq(10^d+x, x=1..10^d-1), d=1..2)]); # Robert Israel, Aug 18 2017

Crossrefs

Cf. A001358, A290751, A290753.

Sequence in context: A205347 A054367 A199225 * A290753 A290361 A254869

Adjacent sequences: A290749 A290750 A290751 * A290753 A290754 A290755

Keyword

nonn,base

Author

N. J. A. Sloane, Aug 17 2017, following a suggestion from J. M. Bergot.

Status

approved