|
Search: id:A162146
|
|
|
| A162146 |
|
a(n) = the smallest positive integer divisible by exactly n distinct primes, where each of these primes has the same number of digits when written in binary. |
|
+0
1
|
|
| 1, 2, 6, 7429, 215441, 6678671, 9586934839, 584803025179, 1985383050388741, 204494454190040323, 21880906598334314561, 2385018819218440287149, 269507126571683752447837, 34227405074603836560875299
(list; graph; listen)
|
|
|
OFFSET
|
0,2
|
|
|
COMMENT
|
Each term of this sequence is square-free.
|
|
EXAMPLE
|
For a(2), 6 = 2 (10_b) * 3 (11_b), For a(3), 7429 = 17 (10001_b) * 19 (10011_b) * 23 (10111_b), For a(4), 215441 = 17 (10001_b) * 19 (10011_b) * 23 (10111_b) * 29 (11101_b), etc. [From Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 16 2009]
|
|
MATHEMATICA
|
f[n_] := Block[{k = 1}, While[p = Select[ Table[i, {i, 2^k, 2^(k + 1) - 1}], PrimeQ@# &]; len = Length@p; len < n, k++ ]; Times @@ Take[p, n]]; Table[ f@n, {n, 0, 15}] [From Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 16 2009]
|
|
CROSSREFS
|
A162145
Sequence in context: A071093 A114045 A116899 this_sequence A055698 A121167 A115658
Adjacent sequences: A162143 A162144 A162145 this_sequence A162147 A162148 A162149
|
|
KEYWORD
|
base,nonn
|
|
AUTHOR
|
Leroy Quet (q1qq2qqq3qqqq(AT)yahoo.com), Jun 25 2009
|
|
EXTENSIONS
|
More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 16 2009
|
|
|
Search completed in 0.002 seconds
|
