A180269 Primes of the form 3^n+3*n+1.

2, 7, 37, 36472996377170786527, 2954312706550833698779, 3990838394187339929534246675572349035477, 2120895147045314119491609587512844743630072393, 228532044137599177017869183161846685251274404207185590172004697234871412029099114059347

Offset: 1

Author

Graziano Aglietti (mg5055(AT)mclink.it), Aug 23 2010

Keywords

• hard
• nonn

Comments

Terms a(9) through a(12) have, respectively, 93, 94, 149, and 156 digits. - Harvey P. Dale, May 11 2013

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..15

Crossrefs

Cf. A176805, A171058.

Programs

Mathematica

Select[Table[3^n+3n+1,{n,0,100}],PrimeQ] (* Harvey P. Dale, May 11 2013 *)

PARI

for(i=0,200,x=3^i+3*i+1;if(isprime(x),print1(x", ")))

Extensions

a(8) from Harvey P. Dale, May 11 2013