|
Search: id:A118727
|
|
|
| A118727 |
|
Primes that are the sum of the numerator and denominator of a harmonic number. |
|
+0
2
|
|
| 2, 5, 17, 37, 197, 503, 9649, 9901, 111431, 1532093, 1556117, 71354639, 392849685203, 67564865715709, 67929521152309, 2551756396706233, 345246028268898566519, 73744425850091533377950933665103
(list; graph; listen)
|
|
|
OFFSET
|
1,1
|
|
|
COMMENT
|
A001008(n) + A002805(n) = A064168(n) is the sum of numerator and denominator in n-th harmonic number H(n) = 1 + 1/2 + 1/3 +...+ 1/n. A064168(n) is prime for n = {1,2,3,4,5,7,9,10,11,14,15,20,27,35,36,39,48..}.
|
|
EXAMPLE
|
H(n) = [ 1/1, 3/2, 11/6, 25/12, 137/60, 49/20, 363/140, 761/280, 7129/2520,... ].
a(1) = 1 + 1 = 2,
a(2) = 3 + 2 = 5,
a(3) = 11 + 6 = 17,
a(4) = 25 + 12 = 37,
a(5) = 137 + 60 = 197,
a(6) = 363 + 140 = 503,
a(7) = 7129 + 2520 = 9649...
|
|
CROSSREFS
|
Cf. A064168, A001008, A002805.
Sequence in context: A002496 A127436 A064168 this_sequence A042361 A114300 A099207
Adjacent sequences: A118724 A118725 A118726 this_sequence A118728 A118729 A118730
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Alexander Adamchuk (alex(AT)kolmogorov.com), May 21 2006
|
|
|
Search completed in 0.002 seconds
|
