OFFSET
1,2
COMMENTS
Numbers n such that (350*10^n + 1)/9 is prime.
Numbers n such that digit 3 followed by n >= 0 occurrences of digit 8 followed by digit 9 is prime.
Numbers corresponding to terms <= 709 are certified primes.
REFERENCES
Klaus Brockhaus and Walter Oberschelp, Zahlenfolgen mit homogenem Ziffernkern, MNU 59/8 (2006), pp. 462-467.
LINKS
FORMULA
a(n) = A102980(n) - 1.
EXAMPLE
3889 is prime, hence 2 is a term.
MATHEMATICA
Select[Range[0, 1000], PrimeQ[(350*10^# + 1)/9]&]
PROG
(PARI) a=39; for(n=0, 1500, if(isprime(a), print1(n, ", ")); a=10*a-1)
(PARI) for(n=0, 1500, if(isprime((350*10^n+1)/9), print1(n, ", ")))
CROSSREFS
KEYWORD
nonn,hard,more
AUTHOR
Klaus Brockhaus and Walter Oberschelp (oberschelp(AT)informatik.rwth-aachen.de), Dec 20 2004
EXTENSIONS
More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008
a(19)-a(26) derived from A102980 by Robert Price, Mar 17 2015
STATUS
approved