OFFSET
1,1
COMMENTS
The next prime has 178 digits. See A078680 for the values of m.
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
N. J. A. Sloane, A Nasty Surprise in a Sequence and Other OEIS Stories, Experimental Mathematics Seminar, Rutgers University, Oct 10 2024, Youtube video; Slides [Mentions this sequence]
MATHEMATICA
Table[m=1; While[! PrimeQ[p = n*2^m + 1], m++]; p, {n, 50}]
PROG
(PARI) a(n)=if(n<0, 0, m=1; while(isprime(n*2^m+1)==0, m++); n*2^m+1)
CROSSREFS
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Dec 17 2002
EXTENSIONS
Edited by T. D. Noe, Feb 25 2011
STATUS
approved