OFFSET
1,3
COMMENTS
Numbers n such that (150*10^n + 3)/9 is prime.
Numbers n such that digit 1 followed by n >= 0 occurrences of digit 6 followed by digit 7 is prime.
Numbers corresponding to terms <= 846 are certified primes.
a(31) > 3*10^5. - Robert Price, Nov 15 2014
REFERENCES
Klaus Brockhaus and Walter Oberschelp, Zahlenfolgen mit homogenem Ziffernkern, MNU 59/8 (2006), pp. 462-467.
LINKS
FORMULA
a(n) = A102940(n+1) - 1. - Robert Price, Nov 15 2014
EXAMPLE
167 is prime, hence 1 is a term.
PROG
(PARI) a=17; for(n=0, 1500, if(isprime(a), print1(n, ", ")); a=10*a-3)
(PARI) for(n=0, 1500, if(isprime((150*10^n+3)/9), print1(n, ", ")))
CROSSREFS
KEYWORD
nonn,hard,more
AUTHOR
Klaus Brockhaus and Walter Oberschelp (oberschelp(AT)informatik.rwth-aachen.de), Dec 28 2004
EXTENSIONS
More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008
a(26)-a(30) derived from A102940 by Robert Price, Nov 15 2014
STATUS
approved