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.

1, 2, 6, 7429, 215441, 6678671, 9586934839, 584803025179, 1985383050388741, 204494454190040323, 21880906598334314561, 2385018819218440287149, 269507126571683752447837, 34227405074603836560875299

Offset

0,2

Comments

Each term of this sequence is squarefree.

Links

Table of n, a(n) for n=0..13.

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. - Robert G. Wilson v, 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}] (* Robert G. Wilson v, Aug 16 2009 *)

Crossrefs

Cf. A162145.

Sequence in context: A116899 A357193 A355556 * A231545 A055698 A121167

Adjacent sequences: A162143 A162144 A162145 * A162147 A162148 A162149

Keyword

base,nonn

Author

Leroy Quet, Jun 25 2009

Extensions

More terms from Robert G. Wilson v, Aug 16 2009

Status

approved