A101570 Indices of primes in sequence defined by A(0) = 53, A(n) = 10*A(n-1) - 17 for n > 0.

0, 2, 18, 108, 128, 279, 386, 446, 486, 1047, 3297, 3459, 9453, 26102, 61692, 66468

Offset

1,2

Comments

Numbers n such that (460*10^n + 17)/9 is prime.

Numbers n such that digit 5 followed by n >= 0 occurrences of digit 1 followed by digit 3 is prime.

Numbers corresponding to terms <= 486 are certified primes.

a(17) > 10^5. - Robert Price, Jun 20 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..16.

Makoto Kamada, Prime numbers of the form 511...113.

Index entries for primes involving repunits.

Formula

a(n) = A103005(n) - 1.

Example

5113 is prime, hence 2 is a term.

Prog

(PARI) a=53; for(n=0, 1500, if(isprime(a), print1(n, ", ")); a=10*a-17)
(PARI) for(n=0, 1500, if(isprime((460*10^n+17)/9), print1(n, ", ")))

Crossrefs

Cf. A000533, A002275, A103005.

Sequence in context: A005969 A094251 A345969 * A006043 A112328 A370732

Adjacent sequences: A101567 A101568 A101569 * A101571 A101572 A101573

Keyword

nonn,more

Author

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

Extensions

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

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

a(15)-a(16) from Robert Price, Jun 20 2015

Status

approved