|
%I #9 Aug 01 2015 21:36:49
%S 1,2,6,7429,215441,6678671,9586934839,584803025179,1985383050388741,
%T 204494454190040323,21880906598334314561,2385018819218440287149,
%U 269507126571683752447837,34227405074603836560875299
%N 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.
%C Each term of this sequence is squarefree.
%e 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
%t 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 *)
%Y Cf. A162145.
%K base,nonn
%O 0,2
%A _Leroy Quet_, Jun 25 2009
%E More terms from _Robert G. Wilson v_, Aug 16 2009
|
