A102013 Indices of primes in sequence defined by A(0) = 17, A(n) = 10*A(n-1) - 33 for n > 0.

0, 1, 3, 4, 11, 59, 108, 180, 244, 411, 886, 2476, 2917, 4621, 6239, 6252, 7683, 14629, 20931, 49800

Offset

1,3

Comments

Numbers n such that (120*10^n + 33)/9 is prime.

Numbers n such that digit 1 followed by n >= 0 occurrences of digit 3 followed by digit 7 is prime.

Numbers corresponding to terms <= 886 are certified primes.

Next term after 7683 is greater than 10000. - Ryan Propper, Jul 01 2005

a(21) > 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

Table of n, a(n) for n=1..20.

Makoto Kamada, Prime numbers of the form 133...337.

Index entries for primes involving repunits.

Formula

a(n) = A102932(n+1) - 1. - Robert Price, Nov 15 2014

Example

137 is prime, hence 1 is a term.

Prog

(PARI) a=17; for(n=0, 1500, if(isprime(a), print1(n, ", ")); a=10*a-33)
(PARI) for(n=0, 1500, if(isprime((120*10^n+33)/9), print1(n, ", ")))

Crossrefs

Cf. A000533, A002275, A102932.

Sequence in context: A041947 A327081 A201970 * A192223 A079940 A225205

Adjacent sequences: A102010 A102011 A102012 * A102014 A102015 A102016

Keyword

nonn,hard,more

Author

Klaus Brockhaus and Walter Oberschelp (oberschelp(AT)informatik.rwth-aachen.de), Dec 28 2004

Extensions

6 more terms, corresponding to probable primes, from Ryan Propper, Jul 01 2005

Edited by T. D. Noe, Oct 30 2008

a(18)-a(20) derived from A102932 by Robert Price, Nov 15 2014

Status

approved