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
Keywords
Examples
a(1)=1 (1 < 2); a(2)=1 (1 < 3); a(3)=4 (4 < 5).
Links
- Marius A. Burtea, Table of n, a(n) for n = 1..10453
Programs
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Magma
[1,1] cat [ p-1: p in PrimesInInterval(4,300)]; // Marius A. Burtea, May 06 2019
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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
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Mathematica
Join[{1, 1}, Prime@Range[3, 65] - 1] (* Harvey P. Dale, Jan 23 2011 *)
Extensions
166 inserted by R. J. Mathar, Oct 31 2009
Comments