

A101017


Indices of primes in sequence defined by A(0) = 93, A(n) = 10*A(n1) + 53 for n > 0.


1



1, 2, 31, 41, 74, 367, 1391, 16349, 49100, 49688, 91839
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OFFSET

1,2


COMMENTS

Numbers n such that (890*10^n  53)/9 is prime.
Numbers n such that digit 9 followed by n >= 0 occurrences of digit 8 followed by digit 3 is prime.
Numbers corresponding to terms <= 367 are certified primes.
a(12) > 10^5.  Robert Price, Nov 12 2015


REFERENCES

Klaus Brockhaus and Walter Oberschelp, Zahlenfolgen mit homogenem Ziffernkern, MNU 59/8 (2006), pp. 462467.


LINKS

Table of n, a(n) for n=1..11.
Makoto Kamada, Prime numbers of the form 988...883.
Index entries for primes involving repunits.


FORMULA

a(n) = A103108(n)  1.


EXAMPLE

9883 is prime, hence 2 is a term.


MATHEMATICA

Flatten[Position[NestList[10#+53&, 93, 1500], _?(PrimeQ[#]&)]]1
Select[Range[0, 100000], PrimeQ[(890*10^#  53)/9] &] (* Robert Price, Nov 12 2015 *)


PROG

(PARI) a=93; for(n=0, 1500, if(isprime(a), print1(n, ", ")); a=10*a+53)
(PARI) for(n=0, 1500, if(isprime((890*10^n53)/9), print1(n, ", ")))


CROSSREFS

Cf. A000533, A002275, A103108.
Sequence in context: A264783 A215031 A120638 * A207973 A193423 A241484
Adjacent sequences: A101014 A101015 A101016 * A101018 A101019 A101020


KEYWORD

nonn,hard,more


AUTHOR

Klaus Brockhaus and Walter Oberschelp (oberschelp(AT)informatik.rwthaachen.de), Nov 27 2004


EXTENSIONS

a(8)a(10) from Kamada data by Ray Chandler, Apr 29 2015
a(11) from Robert Price, Nov 12 2015


STATUS

approved



