|
Search: id:A104873
|
|
|
| A104873 |
|
Concatenations of pairs of primes that differ by 10^12. |
|
+0
1
|
|
| 611000000000061, 1631000000000163, 1931000000000193, 2111000000000211, 2711000000000271, 3311000000000331, 5471000000000547, 6611000000000661, 7511000000000751, 7871000000000787, 9971000000000997, 10511000000001051
(list; graph; listen)
|
|
|
OFFSET
|
1,1
|
|
|
COMMENT
|
Integers in this sequence can never be prime, as they are all multiples of 3. They can be semiprimes, as is the case for Prime(177) concatenated with Prime(37607912056) = 10511000000001051 = 3 * 3503666666667017.
|
|
FORMULA
|
a(n) = Concatenate(P, P+10^12) iff P prime and P+10^12 prime.
|
|
EXAMPLE
|
61 is prime, specifically prime(18) and 61 + 10^12 is prime, specifically prime(7607912020), so their concatenation is in this sequence: 611000000000061. The concatenation is not itself prime, as it equals 3 * 7 * 23 * 1265010351967.
|
|
CROSSREFS
|
Cf. A000040, A001358, A023201, A100750, A103195, A103206, A104718, A104719, A103523, A103534, A103576, A103617.
Sequence in context: A011528 A128769 A086438 this_sequence A088867 A159042 A129935
Adjacent sequences: A104870 A104871 A104872 this_sequence A104874 A104875 A104876
|
|
KEYWORD
|
base,easy,nonn
|
|
AUTHOR
|
Jonathan Vos Post (jvospost3(AT)gmail.com), Mar 29 2005
|
|
|
Search completed in 0.002 seconds
|
