OFFSET
1,2
COMMENTS
Also numbers k such that abs(8*10^k - 71)/9 is a prime.
a(19) > 10^5. - Robert Price, Sep 06 2014
LINKS
FORMULA
a(n) = A056664(n-1) + 1.
MATHEMATICA
Do[ If[ PrimeQ[ 8(10^n - 1)/9 - 7], Print[n]], {n, 0, 15000}]
PROG
(PARI)
for(n=0, 10^4, if(ispseudoprime(abs(8*(10^n-1)/9-7)), print1(n, ", "))) \\ Derek Orr, Sep 06 2014
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert G. Wilson v, Oct 14 2004
EXTENSIONS
a(17)-a(18) from Kamada data by Robert Price, Sep 06 2014
a(19)-a(20) from Kamada data by Tyler Busby, Apr 30 2024
STATUS
approved