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A290753 Semiprimes beginning with 1 such that deleting the 1 leaves a prime. 3
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 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
After deleting the 1, leading zeros are not allowed (see also A290752).
LINKS
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
Sequence in context: A054367 A199225 A290752 * A290361 A254869 A034184
KEYWORD
nonn,base
AUTHOR
N. J. A. Sloane, Aug 17 2017, following a suggestion from J. M. Bergot.
STATUS
approved

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Last modified February 27 04:33 EST 2024. Contains 370362 sequences. (Running on oeis4.)