A101576 Indices of primes in sequence defined by A(0) = 59, A(n) = 10*A(n-1) - 61 for n > 0.

0, 4, 10, 13, 61, 73, 106, 109, 120, 127, 138, 319, 2955, 11115

Offset

1,2

Comments

Numbers n such that (470*10^n + 61)/9 is prime.

Numbers n such that digit 5 followed by n >= 0 occurrences of digit 2 followed by digit 9 is prime.

Numbers corresponding to terms <= 319 are certified primes.

a(15) > 10^5. - Robert Price, Jul 16 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..14.

Makoto Kamada, Prime numbers of the form 522...229.

Index entries for primes involving repunits.

Formula

a(n) = A103011(n) - 1.

Example

522229 is prime, hence 4 is a term.

Mathematica

Select[Range[0, 100000], PrimeQ[(470*10^#+61)/9]&] (* Robert Price, Jul 16 2015 *)

Prog

(PARI) a=59; for(n=0, 1000, if(isprime(a), print1(n, ", ")); a=10*a-61)
(PARI) for(n=0, 1000, if(isprime((470*10^n+61)/9), print1(n, ", ")))

Crossrefs

Cf. A000533, A002275, A103011.

Sequence in context: A173793 A076270 A032821 * A179134 A103044 A310360

Adjacent sequences: A101573 A101574 A101575 * A101577 A101578 A101579

Keyword

nonn,more

Author

Klaus Brockhaus and Walter Oberschelp (oberschelp(AT)informatik.rwth-aachen.de), Dec 09 2004

Extensions

2955 from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 01 2008

a(14) from Kamada data by Ray Chandler, Apr 30 2015

Status

approved