A102024 Indices of primes in sequence defined by A(0) = 17, A(n) = 10*A(n-1) - 3 for n > 0.

0, 1, 2, 4, 8, 10, 13, 31, 53, 54, 59, 152, 199, 460, 568, 839, 846, 1295, 1355, 2006, 2626, 2846, 3109, 6875, 9160, 17764, 33554, 59141, 65772, 280709

Offset: 1

Author

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

Keywords

• nonn
• hard
• more

Comments

Numbers n such that (150*10^n + 3)/9 is prime.

Numbers n such that digit 1 followed by n >= 0 occurrences of digit 6 followed by digit 7 is prime.

Numbers corresponding to terms <= 846 are certified primes.

a(31) > 3*10^5. - Robert Price, Nov 15 2014

Examples

			167 is prime, hence 1 is a term.
		

References

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

Links

• Makoto Kamada, Prime numbers of the form 166...667.
• Index entries for primes involving repunits

Crossrefs

Cf. A000533, A002275, A102940.

Programs

PARI

a=17;for(n=0,1500,if(isprime(a),print1(n,","));a=10*a-3)

PARI

for(n=0,1500,if(isprime((150*10^n+3)/9),print1(n,",")))

Formula

a(n) = A102940(n+1) - 1. - Robert Price, Nov 15 2014

Extensions

More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008

a(26)-a(30) derived from A102940 by Robert Price, Nov 15 2014