OFFSET
1,2
COMMENTS
Numbers n such that (590*10^n - 41)/9 is prime.
Numbers n such that digit 6 followed by n >= 0 occurrences of digit 5 followed by digit 1 is prime.
Numbers corresponding to terms <= 680 are certified primes.
REFERENCES
Klaus Brockhaus and Walter Oberschelp, Zahlenfolgen mit homogenem Ziffernkern, MNU 59/8 (2006), pp. 462-467.
LINKS
FORMULA
a(n) = A103038(n+1) - 1.
EXAMPLE
65551 is prime, hence 3 is a term.
MATHEMATICA
Select[Range[0, 100000], PrimeQ[(590*10^# - 41)/9] &] (* Robert Price, Sep 11 2015 *)
PROG
(PARI) a=61; for(n=0, 1500, if(isprime(a), print1(n, ", ")); a=10*a+41)
(PARI) for(n=0, 1500, if(isprime((590*10^n-41)/9), print1(n, ", ")))
CROSSREFS
KEYWORD
nonn,hard,more
AUTHOR
Klaus Brockhaus and Walter Oberschelp (oberschelp(AT)informatik.rwth-aachen.de), Dec 06 2004
EXTENSIONS
More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 01 2008
a(17)-a(23) from Kamada data by Ray Chandler, Apr 30 2015
a(24) from Robert Price, Sep 11 2015
STATUS
approved