|
Search: id:A111489
|
|
|
| A111489 |
|
Numbers n such that the n-th composite number + the n-th prime number is prime. |
|
+0
1
|
|
| 13, 31, 47, 67, 79, 89, 97, 103, 113, 149, 173, 179, 211, 223, 241, 277, 313, 349, 359, 379, 449, 457, 487, 503, 509, 631, 743, 769, 797, 809, 887, 937, 967, 1009, 1049, 1109, 1123, 1213, 1231, 1277, 1289, 1319, 1409, 1429, 1453, 1471, 1489, 1543, 1571, 1663
(list; graph; listen)
|
|
|
OFFSET
|
1,1
|
|
|
COMMENT
|
Conjecture: The number of primes in this sequence is infinite.
|
|
EXAMPLE
|
The third prime is 5, the third composite is 8, 8+5=13, the first entry.
|
|
PROGRAM
|
(PARI) g(n)=for(x=1, n, y=prime(x)+composite(x); if(isprime(y), print1(y", ")))
|
|
CROSSREFS
|
Sequence in context: A080387 A097443 A100589 this_sequence A106294 A101649 A063305
Adjacent sequences: A111486 A111487 A111488 this_sequence A111490 A111491 A111492
|
|
KEYWORD
|
easy,nonn
|
|
AUTHOR
|
Cino Hilliard (hillcino368(AT)gmail.com), Nov 15 2005
|
|
|
Search completed in 0.002 seconds
|
