A338048 a(n) is the smallest number that is not less than n such that n*a(n)+2 is semiprime.

2, 2, 4, 5, 11, 6, 7, 9, 13, 12, 11, 12, 19, 16, 19, 17, 17, 18, 20, 21, 23, 30, 24, 26, 32, 34, 27, 30, 29, 36, 37, 36, 35, 36, 35, 41, 37, 40, 43, 41, 43, 42, 43, 45, 47, 50, 48, 48, 51, 52, 51, 57, 53, 54, 55, 57, 59, 60, 61, 60, 63, 76, 64, 65, 65, 66, 75

Offset: 1

Author

N. J. A. Sloane, Oct 08 2020, based on an email from Todor Szimeonov, Oct 07 2020

Keywords

• nonn

Comments

Motivated by a question about arranging square tiles in a rectangle.

Crossrefs

Cf. A001358, A338049.