

A102028


Indices of primes in sequence defined by A(0) = 19, A(n) = 10*A(n1)  11 for n > 0.


1



0, 1, 7, 9, 24, 49, 75, 103, 4405, 8934, 25999, 31651
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OFFSET

1,3


COMMENTS

Numbers n such that (160*10^n + 11)/9 is prime.
Numbers n such that digit 1 followed by n >= 0 occurrences of digit 7 followed by digit 9 is prime.
Numbers corresponding to terms <= 103 are certified primes.
a(13) > 10^5.  Robert Price, Feb 07 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..12.
Makoto Kamada, Prime numbers of the form 177...779.
Index entries for primes involving repunits.


FORMULA

a(n) = A102943(n)  1.


EXAMPLE

179 is prime, hence 1 is a term.


PROG

(PARI) a=19; for(n=0, 1500, if(isprime(a), print1(n, ", ")); a=10*a11)
(PARI) for(n=0, 1500, if(isprime((160*10^n+11)/9), print1(n, ", ")))


CROSSREFS

Cf. A000533, A002275, A102943.
Sequence in context: A303188 A029633 A049301 * A265990 A125260 A192859
Adjacent sequences: A102025 A102026 A102027 * A102029 A102030 A102031


KEYWORD

nonn,hard,more


AUTHOR

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


EXTENSIONS

More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008
a(11)a(12) derived from A102943 by Robert Price, Feb 07 2015


STATUS

approved



