|
%I #9 Jun 01 2013 17:45:24
%S 19,52489,59296646043258913,3140085798164163223281069127,
%T 281013956365219695455558985684629594690518822413326510467
%N Primes of the form n*3^n + 1.
%C Similar to A060353, and to the Woodall primes A050918.
%e 19 = 2*3^2 + 1; 52489 = 8*3^8 + 1; a(3) = 32*3^32 + 1; a(4) = 54*3^54 + 1.
%p #choose N large, then S is the desired set
%p f:=n->n*3^n + 1:
%p S:={}:
%p for n from 0 to N do if(isprime(f(n))) then S:=S union {f(n)}: fi: od
%t Select[Table[n*3^n + 1, {n, 0, 580}], PrimeQ] (* _Jayanta Basu_, Jun 01 2013 *)
%Y Cf. A060353, A050918.
%K nonn
%O 1,1
%A _Patrick Devlin_, Apr 26 2012
| 