A082717 -id:A082717 - cp's OEIS frontend

A056264 Indices of primes in sequence defined by A(0) = 99, A(n) = 10*A(n-1) - 71 for n > 0.

1, 245, 1139, 10393, 43879

Offset: 1

Robert G. Wilson v, Aug 18 2000

Numbers n such that (820*10^n + 71)/9 is a prime.
Numbers n such that digit 9 followed by n >= 0 occurrences of digit 1 followed by digit 9 is prime.
Numbers corresponding to terms <= 1139 are certified primes. For number corresponding to 10393 and larger see P. De Geest, PDP Reference Table.

			919 is prime, hence 1 is a term.

Klaus Brockhaus and Walter Oberschelp, Zahlenfolgen mit homogenem Ziffernkern, MNU 59/8 (2006), pp. 462-467.

Patrick De Geest, PDP Reference Table - 919.
Makoto Kamada, Prime numbers of the form 911...119.
Index entries for primes involving repunits.

Cf. A000533, A002275, A082717.

Flatten[Position[NestList[10#-71&,99,1200],?PrimeQ]]-1 (* _Harvey P. Dale, May 02 2012 *)

a=99;for(n=0,1500,if(isprime(a),print1(n,","));a=10*a-71)

for(n=0,1500,if(isprime((820*10^n+71)/9),print1(n,",")))

a(n) = A082717(n) - 2.

Additional comments from Klaus Brockhaus and Walter Oberschelp (oberschelp(AT)informatik.rwth-aachen.de), Nov 27 2004
Edited by N. J. A. Sloane, Jun 15 2007
One more term from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008
Edited comments section by Patrick De Geest, Nov 02 2014
Edited by Ray Chandler, Nov 04 2014

cp's OEIS Frontend

A056264 Indices of primes in sequence defined by A(0) = 99, A(n) = 10*A(n-1) - 71 for n > 0.

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