|
Search: id:A162409
|
|
|
| A162409 |
|
Semiprimes of the form p*(k*p-1) where k > 1 (and p prime). |
|
+0
1
|
|
| 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; listen)
|
|
|
OFFSET
|
1,1
|
|
|
COMMENT
|
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.
|
|
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.
|
|
PROGRAM
|
(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 };
|
|
CROSSREFS
|
Subsequence of A006881 (product of two distinct primes).
Sequence in context: A064452 A085647 A072901 this_sequence A075777 A167200 A077667
Adjacent sequences: A162406 A162407 A162408 this_sequence A162410 A162411 A162412
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Vassilis Papadimitriou (bpapa(AT)sch.gr), Jul 02 2009
|
|
EXTENSIONS
|
Edited, corrected and extended by Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Jul 06 2009
|
|
|
Search completed in 0.002 seconds
|
