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

1,3

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

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..30.

Makoto Kamada, Prime numbers of the form 166...667.

Index entries for primes involving repunits

Formula

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

Example

167 is prime, hence 1 is a term.

Prog

(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, ", ")))

Crossrefs

Cf. A000533, A002275, A102940.

Sequence in context: A190744 A190751 A030232 * A104197 A323440 A350804

Adjacent sequences: A102021 A102022 A102023 * A102025 A102026 A102027

Keyword

nonn,hard,more

Author

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

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

Status

approved