A086362 a(n) = A085956(3n+1).

5, 17, 239, 41, 131, 1889, 419, 89, 101, 113, 2543, 2789, 149, 881, 173, 9293, 491, 14249, 3191, 1973, 3539, 21377, 7103, 281, 5987, 38153, 317, 2789, 6971, 353, 214943, 42677, 3299, 11801, 2267, 27773, 29867, 10529, 461, 1181, 2663, 129209

Offset: 0

Author

Labos Elemer, Jul 22 2003

Keywords

• nonn

Comments

A086361 and A086362 includes most probably the solvable [or small?] cases of A085956, where n=3k-1 has probably only two solutions, at [k,n,a(n)]=[1,2,13] and at [2,5,31].

Examples

			n=50:3n+1=151,6n+2=302, a(50)=93923 prime with (93922-1)/302=311, prime and with 302.93923+1=28364747 prime; so the {311,93923,28364747} "generalized [short] Cunningham-chain" is defined.
		

Links

• Michael De Vlieger, Table of n, a(n) for n = 0..1000

Crossrefs

Cf. A085956, A086361.

Programs

Mathematica

Table[Function[m, p = 2; While[Nand @@ PrimeQ@ {2 m p + 1, (p - 1)/(2 m)}, p = NextPrime@ p]; p][3 n + 1], {n, 0, 41}] (* Michael De Vlieger, May 15 2017 *)