OFFSET
1,2
COMMENTS
Numbers n such that (350*10^n - 17)/9 is prime.
Numbers n such that digit 3 followed by n >= 0 occurrences of digit 8 followed by digit 7 is prime.
a(5) > 10^5. - Robert Price, Mar 30 2015
REFERENCES
Klaus Brockhaus and Walter Oberschelp, Zahlenfolgen mit homogenem Ziffernkern, MNU 59/8 (2006), pp. 462-467.
LINKS
FORMULA
a(n) = A102979(n+1) - 1.
EXAMPLE
3888887 is prime, hence 5 is a term.
MATHEMATICA
Select[Range[0, 100], PrimeQ[(350*10^# - 17)/9] &]
PROG
(PARI) a=37; for(n=0, 1500, if(isprime(a), print1(n, ", ")); a=10*a+17)
(PARI) for(n=0, 1500, if(isprime((350*10^n-17)/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(3)-a(4) derived from A102979 by Robert Price, Mar 30 2015
STATUS
approved