|
Search: id:A097447
|
|
|
| A097447 |
|
Primes in the concatenation of consecutive prime-sided isosceles triangles. |
|
+0
1
|
|
| 233, 577, 192323, 798383, 109113113, 113127127, 127131131, 149151151, 181191191, 197199199, 223227227, 239241241, 241251251, 337347347, 431433433, 461463463, 479487487, 491499499, 641643643, 643647647, 683691691, 709719719
(list; graph; listen)
|
|
|
OFFSET
|
2,1
|
|
|
COMMENT
|
Are these prime numbers infinite?
|
|
FORMULA
|
Consider triangles with sides (2, 3, 3), (3, 5, 5), .., (x, y, y) where x is prime and y is the next prime after x. Concatenate these sides and output if prime.
|
|
EXAMPLE
|
For side x = 19, y = 23 and 192323 is prime.
|
|
PROGRAM
|
(PARI) f(n) = for(x=1, n, y=Str(prime(x)); y=concat(y, concat(Str(prime(x+1)), Str(prime (x+1)))); if(isprime(eval(y)), print1(y", ")))
|
|
CROSSREFS
|
Adjacent sequences: A097444 A097445 A097446 this_sequence A097448 A097449 A097450
Sequence in context: A105981 A087862 A097446 this_sequence A023338 A108820 A003537
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Cino Hilliard (hillcino368(AT)gmail.com), Aug 23 2004
|
|
|
Search completed in 0.002 seconds
|
