|
Search: id:A078431
|
|
|
| A078431 |
|
Number of permutations p of 1,2,...,n such that both numerator and denominator of the continued fraction [p(1); p(2),...,p(n)] are primes. |
|
+0
3
|
| |
|
|
OFFSET
|
1,4
|
|
|
COMMENT
|
Based on a question from Leroy Quet.
|
|
LINKS
|
Leroy Quet, Home Page (listed in lieu of email address)
|
|
EXAMPLE
|
a(4)=3 because [2;1,3,4]=47/17, [2;3,1,4]=43/19, [4;3,1,2]=47/11
|
|
CROSSREFS
|
Cf. A078432, A078433.
Sequence in context: A157050 A059368 A090694 this_sequence A112534 A006656 A159910
Adjacent sequences: A078428 A078429 A078430 this_sequence A078432 A078433 A078434
|
|
KEYWORD
|
more,nonn
|
|
AUTHOR
|
Reiner Martin (reinermartin(AT)hotmail.com), Dec 30 2002
|
|
|
Search completed in 0.002 seconds
|
