%I #9 May 06 2013 11:12:20

%S 10123457689,10123456789,1023456879,1023456987,1023456897,1023456789,

%T 1023456798,1023457896,1023486975,1023479856,1023458976,1023475968,

%U 1024973568,1023579648,1024897536,1023657984,1032984576,1034698752,1093865472,1074659328,1072963584

%N Smallest pandigital number with exactly n prime factors (with multiplicity).

%C Smallest pandigital n-almost prime.

%F a(n) = MIN{k such that k is in A050278 and bigomega(k) = n}.

%F a(n) = MIN{k such that k is in A050278 and A001222(k) = n}.

%e a(1) = 10123457689 is the least prime pandigital number (A221646), that is, the smallest prime containing all the digits 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9.

%e a(2) = 10123456789 = 919 * 11015731, the smallest pandigital semiprime.

%e a(3) = 1023456879, the smallest pandigital number (A171102) that is 3-almost prime (product of three primes with repetition).

%e a(4) = 1023456987 = 3^2 * 7 * 16245349, which is the smallest pandigital 4-almost prime.

%e a(5) = 1023456897 = 3^3 * 2417 * 15683.

%e a(6) = 1023456789 = 3^4 * 2221 * 5689.

%e a(7) = 1023456798 = 2 * 3^2 * 7 * 13 * 487 * 1283.

%e a(8) = 1023457896 = 2^3 * 3^3 * 59 * 80309.

%t a[n_] := Block[{k = If[n < 3, 10123456789, 1023456789]}, While[ Union@ IntegerDigits@ k != Range[0, 9] || Total[Last /@ FactorInteger[k]] != n, k++]; k]; Array[a, 10] (* _Giovanni Resta_, May 06 2013 *)

%Y Cf. A171102, A221646, A175845.

%K nonn,base,easy

%O 1,1

%A _Jonathan Vos Post_, May 04 2013

%E a(2) corrected and a(9)-a(21) from _Giovanni Resta_, May 06 2013