A318965 -id:A318965 - cp's OEIS frontend

A131931 Smallest number containing exactly n prime factors in its decimal representation.

1, 2, 132, 735, 21372, 271362, 4773132, 113678565, 11317129824

Offset: 0

Reinhard Zumkeller, Jul 30 2007

A131929(a(n)) = n and A131929(m) <> n for m

			a(2) = 2^2 * 3 * 11 = 132 containing 2 and 3;
a(3) = 3 * 5 * 7^2 = 735 containing 3, 5 and 7;
a(4) = 2^2 * 3 * 13 * 137 = 21372 containing 2, 3, 13 and 137;
a(5) = 2 * 3 * 7^2 * 13 * 71 = 271362 containing 2, 3, 7, 13 and 71.

Cf. A131930, A131929, A318965.

Offset changed by and a(6)-a(8) from Giovanni Resta, Sep 06 2018

A319022 a(n) is the smallest number with n distinct prime factors whose decimal representation contains all its prime factors, taking multiplicity into account.

Original entry on oeis.org

2, 119911, 2510, 21372, 1943795, 73171842, 113678565, 13121675970, 297115923720, 73605381139290, 255360234137190, 43759729761726090

Offset: 1

Altug Alkan, Sep 08 2018

A version of A318965.
If a term t is divisible by a prime power p^k, then p must appear at least k times in the decimal representation of t. The copies of p are allowed to overlap; however, in the first 12 terms of the sequence, this does not occur, and only a(2), a(4), and a(9) are nonsquarefree.
a(n) >= A318965(n) by definition. If A318965(n) is squarefree, then a(n) = A318965(n). But a(n) = A318965(n) can also hold for a(n) that is nonsquarefree; e.g., a(4) = A318965(4).

			a(2) = 119911 = 11 * 11 * 991.
a(3) = 2510 = 2 * 5 * 251.
a(4) = 21372 = 2 * 2 * 3 * 13 * 137.
a(5) = 1943795 = 5 * 7 * 19 * 37 * 79.
a(6) = 73171842 = 2 * 3 * 17 * 31 * 73 * 317.
a(7) = 113678565 = 3 * 5 * 7 * 11 * 13 * 67 * 113.

Cf. A083359, A131930, A318965.

Terms computed by Giovanni Resta, Sep 08 2018

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cp's OEIS Frontend

A131931 Smallest number containing exactly n prime factors in its decimal representation.

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