OFFSET
1,2
COMMENTS
Numbers n such that (290*10^n + 43)/9 is prime.
Numbers n such that digit 3 followed by n >= 0 occurrences of digit 2 followed by digit 7 is prime.
Number corresponding to term 41 is a certified prime. No further terms up to 5000.
a(4) > 10^5. - Robert Price, Mar 12 2015
REFERENCES
Klaus Brockhaus and Walter Oberschelp, Zahlenfolgen mit homogenem Ziffernkern, MNU 59/8 (2006), pp. 462-467.
LINKS
FORMULA
a(n) = A102967(n) - 1.
EXAMPLE
37 is prime, hence 0 is a term.
PROG
(PARI) a=37; for(n=0, 1500, if(isprime(a), print1(n, ", ")); a=10*a-43)
(PARI) for(n=0, 1500, if(isprime((290*10^n+43)/9), print1(n, ", ")))
CROSSREFS
KEYWORD
nonn,bref,hard,more
AUTHOR
Klaus Brockhaus and Walter Oberschelp (oberschelp(AT)informatik.rwth-aachen.de), Dec 20 2004
EXTENSIONS
5021 from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008
STATUS
approved