A364242 a(n) is the smallest positive integer such that a(n) and a(n)+2 are both products of n distinct prime factors.

3, 33, 663, 18445, 887313, 84946015, 3086525013, 557027507463, 31110090768183, 3404401335645583, 609352762511672905

Offset

1,1

Links

Table of n, a(n) for n=1..11.

Example

a(2) = 33 = 3 * 11, a(2) + 2 = 35 = 5 * 7.
a(3) = 663 = 3 * 13 * 17, a(3) + 2 = 665 = 5 * 7 * 19.

Prog

(PARI) isok(k, n) = (omega(k)==n) && (omega(k+2)==n) && issquarefree(k) && issquarefree(k+2)
a(n) = my(k=1); while (!isok(k, n), k++); k; \\ Michel Marcus, Jul 16 2023

Crossrefs

Cf. A052215.

Subsequence of A005117.

Sequence in context: A361212 A144756 A336636 * A091462 A340971 A326328

Adjacent sequences: A364239 A364240 A364241 * A364243 A364244 A364245

Keyword

nonn,hard,more

Author

Tomek Czajka, Jul 15 2023

Status

approved