OFFSET
1,2
COMMENTS
Some of the results were computed using the PrimeFormGW (PFGW) primality-testing program. - Hugo Pfoertner, Nov 14 2019
LINKS
S. W. Golomb, Properties of the sequence 3.2^n+1, Math. Comp., 30 (1976), 657-663.
S. W. Golomb, Properties of the sequence 3.2^n+1, Math. Comp., 30 (1976), 657-663. [Annotated scanned copy]
Makoto Kamada, Prime numbers of the form 300...001.
Sabin Tabirca and Kieran Reynolds, Lacunary Prime Numbers.
FORMULA
a(n) = A101823(n) + 1.
EXAMPLE
k = 3 gives (3*10^3+1) = 3000+1 = 3001, which is prime.
MATHEMATICA
Do[ If[ PrimeQ[ 3*10^k + 1], Print[ k ]], {k, 0, 20000}]
PROG
(PARI) is(k)=isprime(3*10^k+1) \\ Charles R Greathouse IV, Feb 17 2017
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Robert G. Wilson v, Aug 22 2000
EXTENSIONS
a(13) & a(14) from Julien Peter Benney (jpbenney(AT)ftml.net), Nov 23 2004
a(15) from Hugo Pfoertner
a(16) & a(17) from Robert G. Wilson v, Jan 18 2005
a(18) from Roman Makarchuk, Dec 05 2008 confirmed as next term by Ray Chandler, Mar 02 2012
a(19) from Alexander Gramolin, Feb 24 2012 confirmed as next term by Ray Chandler, Mar 02 2012
a(20)-a(21) from Kamada data by Robert Price, Jan 26 2015
STATUS
approved