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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

%I

%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

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Last modified July 18 10:35 EDT 2019. Contains 325138 sequences. (Running on oeis4.)