OFFSET
1,1
COMMENTS
Numbers n such that (280*10^n + 71)/9 is prime.
Numbers n such that digit 3 followed by n >= 0 occurrences of digit 1 followed by digit 9 is prime.
Numbers corresponding to terms <= 796 are certified primes.
REFERENCES
Klaus Brockhaus and Walter Oberschelp, Zahlenfolgen mit homogenem Ziffernkern, MNU 59/8 (2006), pp. 462-467.
LINKS
FORMULA
a(n) = A102965(n+1) - 1.
EXAMPLE
3119 is prime, hence 2 is a term.
PROG
(PARI) a=39; for(n=0, 3200, if(isprime(a), print1(n, ", ")); a=10*a-71)
(PARI) for(n=0, 3200, if(isprime((280*10^n+71)/9), print1(n, ", ")))
CROSSREFS
KEYWORD
nonn,hard,more
AUTHOR
Klaus Brockhaus and Walter Oberschelp (oberschelp(AT)informatik.rwth-aachen.de), Dec 20 2004
EXTENSIONS
a(5)-a(7) derived from A102965 by Robert Price, Jan 26 2015
STATUS
approved