A105792 Largest prime <= numbers congruent (2,4) mod 6 (duplicates removed).

2, 3, 7, 13, 19, 23, 31, 37, 43, 47, 53, 61, 67, 73, 79, 83, 89, 97, 103, 109, 113, 127, 131, 139, 151, 157, 163, 167, 173, 181, 193, 199, 211, 223, 229, 233, 241, 251, 257, 263, 271, 277, 283, 293, 307, 313, 317, 331, 337, 349, 353, 359, 367, 373, 379, 383, 389

Offset

1,1

Comments

Except for the first terms, largest prime p is at least < two numbers congruent (2,4) mod 6.

Links

Table of n, a(n) for n=1..57.

Example

7 is in the sequence because 7 is the largest prime < 8 which is a number congruent (2,4) mod 6.

Mathematica

pp[n_] := Block[{k = n}, While[ ! PrimeQ[k], k-- ]; k]; Union[pp /@ Select[Range[400], MemberQ[{2, 4}, Mod[ #, 6]] &]] (* Ray Chandler, Oct 17 2006 *)
Union[Abs[NextPrime[#, -1]&/@Select[Range[400], MemberQ[{2, 4}, Mod[ #, 6]]&]]]  Harvey P. Dale, May 17 2012

Crossrefs

Cf. A105399, A105575.

Sequence in context: A329416 A155479 A019411 * A130903 A068828 A100764

Adjacent sequences: A105789 A105790 A105791 * A105793 A105794 A105795

Keyword

easy,nonn

Author

Giovanni Teofilatto, May 05 2005

Extensions

Extended by Ray Chandler, Oct 17 2006

Status

approved