

A133609


Numbers n such that n, n+2 and n+4 are consecutive semiprimes.


1



183, 287, 319, 411, 413, 469, 515, 533, 579, 667, 685, 789, 813, 1055, 1077, 1133, 1145, 1165, 1203, 1253, 1313, 1347, 1383, 1385, 1387, 1389, 1561, 1685, 1687, 1793, 1795, 1817, 1839, 1849, 1919, 1937, 1957, 1959, 2045, 2047, 2155, 2227, 2315, 2317
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OFFSET

1,1


COMMENTS

Terms n in A136196 such that n+2 are also in A136196.
All terms are odd, so it is a subsequence of A161945.  Michel Marcus, Oct 15 2013


LINKS

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000


EXAMPLE

183, 185 and 187 are 59th, 60th and 61st semiprimes,
287, 289 and 291 are 89th, 90th and 91st semiprimes,
319, 321 and 323 are 101st, 102nd and 103rd semiprimes.


PROG

(PARI) isok(n) = (bigomega(n) == 2) && (bigomega(n+1) != 2) && (bigomega(n+2) == 2) && (bigomega(n+3) != 2) && (bigomega(n+4) == 2); \\ Michel Marcus, Oct 15 2013


CROSSREFS

Cf. A136196.
Sequence in context: A248628 A217608 A264779 * A305349 A030465 A147270
Adjacent sequences: A133606 A133607 A133608 * A133610 A133611 A133612


KEYWORD

nonn


AUTHOR

Zak Seidov, Dec 28 2007


STATUS

approved



