|
Search: id:A133597
|
|
|
| A133597 |
|
Array of semiprimes, read by antidiagonals, where row k is the first of pairs of consecutive semiprimes j and j+k. |
|
+0
1
|
|
| 9, 4, 14, 35, 49, 21, 215, 46, 55, 25, 69, 299, 62, 91, 33, 15, 77, 1135, 74, 119, 34, 26, 123, 106, 1343, 82, 143, 38, 169, 39, 371, 161, 1835, 115, 159, 57, 146, 437, 134, 377, 178, 1891, 155, 183, 85, 237, 226, 458, 187, 505, 221, 1939, 166, 185, 86
(list; graph; listen)
|
|
|
OFFSET
|
1,1
|
|
|
COMMENT
|
Every semiprime that occurs in this table occurs only once. The semiprimes which are not in this table (first 10 rows only) begin: 6, 10, 22, 51, 55, 58, 65, 87, ... leading to the question: which semiprimes occur nowhere in the complete table? Note that similar tables exist for k-almost primes (integers with exactly k prime factors, with multiplicity), this being the k=2 slice of a 3-dimensional array..
|
|
EXAMPLE
|
The array begins:
==================================================================
n=......1....2.....3....4....5....6....7....8....9...10
==================================================================
k=1.|...9...14....21...25...33...34...38...57...85...86....A070552
k=2.|...4...49....55...91..119..143..159..183..185..203....A136196
k=3.|..35...46....62...74...82..115..155..166..206..259....
k=4.|.215..299..1135.1343.1835.1891.1939.3095.3153.4411....
k=5.|..69...77...106..161..178..221..254..309..314..329....
k=6.|..15..123...371..377..505..511..545..573..591..649....
k=7.|..26...39...134..187..194..267..519..566..655..771....
k=8.|.169..437...458..614..723..737..905..965.1047.1059....
k=9.|.146..226...278..346.1018.1177.1273.1546.1594.1865....
k=10|.237..427..1027.1101.1661.2723.2747.3173.3295.3669....
==================================================================
|
|
CROSSREFS
|
Cf. A001358, A070552, A136196.
Sequence in context: A019617 A021517 A088701 this_sequence A075066 A061363 A100077
Adjacent sequences: A133594 A133595 A133596 this_sequence A133598 A133599 A133600
|
|
KEYWORD
|
easy,nonn
|
|
AUTHOR
|
Jonathan Vos Post (jvospost3(AT)gmail.com), Dec 27 2007
|
|
|
Search completed in 0.002 seconds
|
