A290753 Semiprimes beginning with 1 such that deleting the 1 leaves a prime.

15, 111, 119, 123, 129, 141, 143, 159, 161, 183, 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, 1569, 1577, 1631, 1641, 1643

Offset

1,1

Comments

After deleting the 1, leading zeros are not allowed (see also A290752).

Links

David A. Corneth, Table of n, a(n) for n = 1..10000

Prog

(PARI) first(n) = {my(v = vector(n), i = 1); forprime(p = 2, oo, p1 = 10^(#digits(p)) + p; if(bigomega(p1) == 2, v[i] = p1; i++; if(i>#v, return(v))))} \\ David A. Corneth, Aug 26 2017

Crossrefs

Cf. A001358, A290751, A290752.

Sequence in context: A054367 A199225 A290752 * A290361 A254869 A034184

Adjacent sequences: A290750 A290751 A290752 * A290754 A290755 A290756

Keyword

nonn,base

Author

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

Status

approved