OFFSET
1,2
COMMENTS
Numbers k such that the digits 63 followed by k-1 occurrences of the digit 0 followed by the digit 1 is prime (see Example section).
a(31) > 10^5.
LINKS
Makoto Kamada, Search for 630w1.
EXAMPLE
2 is in this sequence because 63*10^2+1 = 6301 is prime.
Initial terms and associated primes:
a(1) = 1, 631;
a(2) = 2, 6301;
a(3) = 12, 63000000000001;
a(4) = 21, 63000000000000000000001;
a(5) = 27, 63000000000000000000000000001, etc.
MATHEMATICA
Select[Range[0, 100000], PrimeQ[63*10^#+1] &]
PROG
(PARI) is(n)=ispseudoprime(63*10^n+1) \\ Charles R Greathouse IV, Jun 13 2017
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Robert Price, Apr 05 2016
STATUS
approved