A133387 Greatest prime p such that 6*n-p is prime.

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

Offset: 1

Author

Pierre CAMI, Nov 23 2007

Keywords

• nonn
• easy

Links

• Nathaniel Johnston, Table of n, a(n) for n = 1..10000

Programs

Maple

A133387 := proc(n) local p: p:=prevprime(6*n): while(not isprime(6*n-p))do p:=prevprime(p): od: return p: end: seq(A133387(n),n=1..100); # Nathaniel Johnston, Jun 25 2011

Mathematica

gpp[n_]:=Module[{p=NextPrime[6n,-1]},While[!PrimeQ[6n-p],p=NextPrime[ p,-1]];p]; Array[ gpp,60] (* Harvey P. Dale, Jan 03 2024 *)