A105575 Largest primes < numbers of the form 6k (duplicates removed).

5, 11, 17, 23, 29, 31, 41, 47, 53, 59, 61, 71, 73, 83, 89, 101, 107, 113, 131, 137, 139, 149, 151, 157, 167, 173, 179, 181, 191, 197, 199, 211, 227, 233, 239, 241, 251, 257, 263, 269, 271, 281, 283, 293, 311, 317, 331, 337, 347, 353, 359, 367, 373, 383, 389

Offset: 1

Author

Giovanni Teofilatto, May 03 2005

Keywords

• easy
• nonn

Examples

			11 is in the sequence because 11 is the largest prime < 12 = 6*2.
		

Crossrefs

Cf. A105399.

Programs

Mathematica

PrevPrim[n_] := Block[{k = n - 1}, While[ !PrimeQ[k], k-- ]; k]; Union[ Table[ PrevPrim[6n], {n, 65}]] (* Robert G. Wilson v, May 21 2005 *)
NextPrime[#,-1]&/@(6*Range[100])//Union (* Harvey P. Dale, Sep 23 2017 *)

Extensions

Corrected and extended by Robert G. Wilson v, May 21 2005

Edited, corrected and extended by Ray Chandler, Oct 17 2006