A102023 Indices of primes in sequence defined by A(0) = 13, A(n) = 10*A(n-1) + 33 for n > 0.

0, 1, 2, 17, 176, 323, 387, 391, 403, 530, 1082, 12545, 22442, 54387, 72915, 185519

Offset

1,3

Comments

Numbers n such that (150*10^n - 33)/9 is prime.

Numbers n such that digit 1 followed by n >= 0 occurrences of digit 6 followed by digit 3 is prime.

Numbers corresponding to terms <= 530 are certified primes.

a(16) > 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..16.

Makoto Kamada, Prime numbers of the form 166...663.

Index entries for primes involving repunits

Formula

a(n) = A102939(n) - 1. - Robert Price, Nov 15 2014

Example

163 is prime, hence 1 is a term.

Prog

(PARI) a=13; for(n=0, 1500, if(isprime(a), print1(n, ", ")); a=10*a+33)
(PARI) for(n=0, 1500, if(isprime((150*10^n-33)/9), print1(n, ", ")))

Crossrefs

Cf. A000533, A002275, A102939.

Sequence in context: A046909 A041879 A011550 * A212833 A230087 A058010

Adjacent sequences: A102020 A102021 A102022 * A102024 A102025 A102026

Keyword

nonn,hard,more

Author

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

Extensions

a(12)-a(15) derived from A102939 by Robert Price, Nov 15 2014

a(16) derived from A102939 by Tyler Busby, Apr 16 2024

Status

approved