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A084632 Semiprimes such that when they are concatenated with their 10's complement, which also must be a semiprime, the result is a prime. +0
1
49, 91, 169, 237, 319, 321, 329, 377, 411, 417, 473, 529, 553, 583, 597, 629, 697, 713, 763, 779, 791, 817, 913, 923, 949, 1203, 1257, 1273, 1339, 1347, 1379, 1389, 1497, 1501, 1509, 1529, 1589, 1633, 1739, 1803, 1841, 1967, 1969, 2019, 2103, 2173, 2219 (list; graph; listen)
OFFSET

1,1

EXAMPLE

a(3)=169 because 169 is a semiprime and 1000-169 = 831 is a semiprime, while 169831 is a prime.

CROSSREFS

Cf. A001358.

Sequence in context: A118886 A108164 A020158 this_sequence A020176 A146064 A031180

Adjacent sequences: A084629 A084630 A084631 this_sequence A084633 A084634 A084635

KEYWORD

nonn,base

AUTHOR

Jason Earls (zevi_35711(AT)yahoo.com), Jun 28 2003

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Last modified December 2 15:58 EST 2008. Contains 150992 sequences.


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