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A162409
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Semiprimes of the form p*(k*p-1) where k > 1 (and p prime).
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0
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6, 10, 14, 15, 22, 26, 33, 34, 38, 46, 51, 58, 62, 69, 74, 82, 86, 87, 91, 94, 95, 106, 118, 122, 123, 134, 141, 142, 145, 146, 158, 159, 166, 177, 178, 194, 202, 206, 213, 214, 218, 226, 249, 254, 262, 267, 274, 278, 287, 295, 298, 302, 303, 314, 321, 326, 334
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Regarding k = 1: 3 is the only prime p such that p-1 is prime, so 3*(1*3-1) = 6. But 6 is a term for p = 2 and k = 2 (see example), therefore the sequence does not change if k = 1 is allowed in the definition.
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EXAMPLE
| For p = 2 and k = 2 we have 2*(2*2-1) = 6, so 6 is a term. For p = 3 and k = 6 we have 3*(6*3-1) = 51, so 51 is a term.
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PROG
| (MAGMA) m:=170; { s: p, q in PrimesUpTo(m) | s le 2*m and exists(t){ k: k in [2..p*q div 2] | q eq p*k-1 } where s is p*q };
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CROSSREFS
| Subsequence of A006881 (product of two distinct primes).
Sequence in context: A064452 A085647 A072901 * A183072 A193416 A075777
Adjacent sequences: A162406 A162407 A162408 * A162410 A162411 A162412
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KEYWORD
| nonn
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AUTHOR
| Vassilis Papadimitriou (bpapa(AT)sch.gr), Jul 02 2009
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EXTENSIONS
| Edited, corrected and extended by Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Jul 06 2009
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