A175845 -id:A175845 - cp's OEIS frontend

A225295 Pandigital numbers with exactly 4 prime factors (with multiplicity).

1023456987, 1023458679, 1023458967, 1023465798, 1023465897, 1023465978, 1023465987, 1023467589, 1023467859, 1023468579, 1023468597, 1023468795, 1023469758, 1023478569, 1023479586, 1023479865, 1023485967, 1023486579, 1023486957, 1023487659, 1023487965, 1023489657, 1023495678

Offset: 1

Jonathan Vos Post, May 04 2013

			a(1) = 1023456987 = 3^2 * 7 * 16245349.
a(2) = 1023458679 = 3^3 * 37905877.
a(3) = 1023458967 = 3^2 * 113 * 1006351.
a(4) = 1023465897 = 3^2 * 6379 * 17827.
a(5) = 1023465987 = 3^2 * 53 * 2145631.
a(511032) = 10123456987 = 7^2 * 9833 * 21011.

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Cf. A001358, A014613, A221646.
Cf. A050288 (pandigital primes), A175845 (pandigital numbers).
Cf. A171102 (3-almost primes).

is(n)=#vecsort(digits(n),,8)>9 && bigomega(n)==4 \\ Charles R Greathouse IV, May 04 2013

A014613 INTERSECTION A171102.

a(n) ~ 6n log n / (log log n)^3. - Charles R Greathouse IV, May 04 2013

a(6)-a(23) from Charles R Greathouse IV, May 04 2013

A225298 Smallest pandigital number with exactly n prime factors (with multiplicity).

Original entry on oeis.org

10123457689, 10123456789, 1023456879, 1023456987, 1023456897, 1023456789, 1023456798, 1023457896, 1023486975, 1023479856, 1023458976, 1023475968, 1024973568, 1023579648, 1024897536, 1023657984, 1032984576, 1034698752, 1093865472, 1074659328, 1072963584

Offset: 1

Jonathan Vos Post, May 04 2013

Smallest pandigital n-almost prime.

			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.
a(2) = 10123456789 = 919 * 11015731, the smallest pandigital semiprime.
a(3) = 1023456879, the smallest pandigital number (A171102) that is 3-almost prime (product of three primes with repetition).
a(4) = 1023456987 = 3^2 * 7 * 16245349, which is the smallest pandigital 4-almost prime.
a(5) = 1023456897 = 3^3 * 2417 * 15683.
a(6) = 1023456789 = 3^4 * 2221 * 5689.
a(7) = 1023456798 = 2 * 3^2 * 7 * 13 * 487 * 1283.
a(8) = 1023457896 = 2^3 * 3^3 * 59 * 80309.

Cf. A171102, A221646, A175845.

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 *)

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

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

a(2) corrected and a(9)-a(21) from Giovanni Resta, May 06 2013

cp's OEIS Frontend

A225295 Pandigital numbers with exactly 4 prime factors (with multiplicity).

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