A318965 a(n) is the smallest number containing all its n prime factors in its decimal representation.

2, 135, 735, 21372, 271362, 4773132, 113678565, 11317129824, 131175822960, 7113719552940, 255360234137190, 12411792985131540

Offset

1,1

Links

Table of n, a(n) for n=1..12.

Example

a(2) = 135 = 3^3 * 5,
a(3) = 735 = 3 * 5 * 7^2,
a(4) = 21372 = 2^2 * 3 * 13 * 137,
a(5) = 271362 = 2 * 3 * 7^2 * 13 * 71,
a(6) = 4773132 = 2^2 * 3^2 * 7 * 13 * 31 * 47.
a(7) = 113678565 = 3 * 5 * 7 * 11 * 13 * 67 * 113.

Mathematica

a[n_] := Block[{k=1, s, f}, While[True, k++; If[Length[f = FactorInteger[k]] == n, s = ToString@k; If[AllTrue[First /@ f, StringPosition[s, ToString@ #] != {} &], Break[]]]]; k]; Array[a, 5]

Crossrefs

Cf. A131929, A131930, A131931, A239060, A115738.

Sequence in context: A014315 A221468 A327911 * A097641 A065963 A353012

Adjacent sequences: A318962 A318963 A318964 * A318966 A318967 A318968

Keyword

nonn,base,more

Author

Giovanni Resta, Sep 06 2018

Status

approved