|
Search: id:A088648
|
|
|
| A088648 |
|
a(1) = 1, then the smallest odd number not occurring earlier such that the concatenation a(r), a(s) is composite for all s > r. |
|
+0
1
|
|
| 1, 5, 11, 15, 19, 25, 35, 45, 55, 65, 75, 85, 95, 105, 115, 125, 135, 145, 155, 165, 175, 185, 195, 205, 215, 225, 235, 245, 255, 265, 275, 285, 295, 305, 315, 325, 335, 345, 355, 365, 375, 385, 395, 405, 415, 425, 435, 445, 455, 465, 475, 485, 495, 505, 515
(list; graph; listen)
|
|
|
OFFSET
|
0,2
|
|
|
COMMENT
|
The sequence is infinite with trivial terms of the form 10k+5. Subsidiary sequence: sequence of nontrivial terms. Conjecture: the subsidiary sequence is infinite.
|
|
EXAMPLE
|
a(5) = 19 as 119, 519,1119,1519, etc. are all composite.
|
|
CROSSREFS
|
Cf. A088647.
Sequence in context: A137006 A137003 A164355 this_sequence A075628 A036787 A154503
Adjacent sequences: A088645 A088646 A088647 this_sequence A088649 A088650 A088651
|
|
KEYWORD
|
base,nonn
|
|
AUTHOR
|
Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Oct 29 2003
|
|
EXTENSIONS
|
More terms from David Wasserman (wasserma(AT)spawar.navy.mil), Aug 17 2005
|
|
|
Search completed in 0.002 seconds
|
