A086361 a(n)=A085956(3n).
13, 61, 127, 73, 61, 397, 211, 97, 163, 181, 463, 5689, 547, 1093, 271, 673, 1123, 10909, 229, 241, 4663, 661, 967, 1873, 7951, 1093, 16363, 5209, 349, 541, 373, 7873, 397, 409, 421, 433, 4219, 9349, 15679, 1201, 1723, 7309, 15739, 3433, 811, 1933
Offset: 1
Keywords
Examples
n=144:3n=432,6n=864, a(144)=120097 prime with (120097-1)/864=139 prime and with 864.12097+1=103763809 prime.
Programs
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PARI
a(n) = {n = 3*n; p = 2; while (!(isprime(2*n*p+1) && (type(q=(p-1)/(2*n))== "t_INT") && isprime(q)), p = nextprime(p+1)); p;} \\ Michel Marcus, Feb 25 2014