A101151 Indices of primes in sequence defined by A(0) = 73, A(n) = 10*A(n-1) + 53 for n > 0.

0, 2, 5, 59, 287, 1313, 1727, 2492, 13892, 13943, 17099, 70226

Offset

1,2

Comments

Numbers n such that (710*10^n - 53)/9 is prime.

Numbers n such that digit 7 followed by n >= 0 occurrences of digit 8 followed by digit 3 is prime.

Numbers corresponding to terms <= 287 are certified primes.

a(13) > 10^5. - Robert Price, Oct 06 2015

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..12.

Makoto Kamada, Prime numbers of the form 788...883.

Index entries for primes involving repunits.

Formula

a(n) = A103066(n+1) - 1.

Example

7888883 is prime, hence 5 is a term.

Mathematica

Select[Range[0, 100000], PrimeQ[(710*10^# - 53)/9] &] (* Robert Price, Oct 06 2015 *)

Prog

(PARI) a=73; for(n=0, 1500, if(isprime(a), print1(n, ", ")); a=10*a+53)
(PARI) for(n=0, 1500, if(isprime((710*10^n-53)/9), print1(n, ", ")))

Crossrefs

Cf. A000533, A002275, A103066.

Sequence in context: A339167 A042161 A176142 * A138788 A030244 A004150

Adjacent sequences: A101148 A101149 A101150 * A101152 A101153 A101154

Keyword

nonn,hard,more

Author

Klaus Brockhaus and Walter Oberschelp (oberschelp(AT)informatik.rwth-aachen.de), Dec 03 2004

Extensions

More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 01 2008

a(9)-a(11) from Kamada data by Ray Chandler, Apr 30 2015

a(12) from Robert Price, Oct 06 2015

Status

approved