A156037 Largest nonprime < n-th prime.

1, 1, 4, 6, 10, 12, 16, 18, 22, 28, 30, 36, 40, 42, 46, 52, 58, 60, 66, 70, 72, 78, 82, 88, 96, 100, 102, 106, 108, 112, 126, 130, 136, 138, 148, 150, 156, 162, 166, 172, 178, 180, 190, 192, 196, 198, 210, 222, 226, 228, 232, 238, 240, 250, 256, 262, 268, 270, 276, 280, 282

Offset

1,3

Comments

Essentially the same as A006093.

Links

Marius A. Burtea, Table of n, a(n) for n = 1..10453

Example

a(1)=1 (1 < 2); a(2)=1 (1 < 3); a(3)=4 (4 < 5).

Maple

A156037 := proc(n) local a; for a from ithprime(n)-1 by -1 do if not isprime(a) then return a ; end if; end do: end proc: seq(A156037(n), n=1..80) ; # R. J. Mathar, Oct 30 2009

Mathematica

Join[{1, 1}, Prime@Range[3, 65] - 1]  (* Harvey P. Dale, Jan 23 2011 *)

Prog

(Magma) [1, 1] cat [ p-1: p in PrimesInInterval(4, 300)]; // Marius A. Burtea, May 06 2019

Crossrefs

Cf. A006093, A165972.

Sequence in context: A353465 A310578 A165972 * A089079 A310579 A242877

Adjacent sequences: A156034 A156035 A156036 * A156038 A156039 A156040

Keyword

nonn

Author

Juri-Stepan Gerasimov, Oct 30 2009

Extensions

166 inserted by R. J. Mathar, Oct 31 2009

Status

approved