|
| |
|
|
A102030
|
|
Indices of primes in sequence defined by A(0) = 13, A(n) = 10*A(n-1) + 53 for n > 0.
|
|
1
|
|
|
|
0, 15, 21, 27, 33, 89, 2067, 2373, 2853, 3719, 4241, 22665, 29291, 29507
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
1,2
|
|
|
COMMENTS
|
Numbers n such that (170*10^n - 53)/9 is prime.
Numbers n such that digit 1 followed by n >= 0 occurrences of digit 8 followed by digit 3 is prime.
Numbers corresponding to terms <= 89 are certified primes.
a(15) > 10^5. - Robert Price, Feb 11 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 188...883.
Index entries for primes involving repunits.
|
|
|
FORMULA
|
a(n) = A102944(n) - 1.
|
|
|
EXAMPLE
|
13 is prime, hence 0 is a term.
|
|
|
PROG
|
(PARI) a=13; for(n=0, 1500, if(isprime(a), print1(n, ", ")); a=10*a+53)
(PARI) for(n=0, 1500, if(isprime((170*10^n-53)/9), print1(n, ", ")))
|
|
|
CROSSREFS
|
Cf. A000533, A002275, A102944.
Sequence in context: A072974 A226025 A082686 * A168104 A026048 A195527
Adjacent sequences: A102027 A102028 A102029 * A102031 A102032 A102033
|
|
|
KEYWORD
|
nonn,hard,more
|
|
|
AUTHOR
|
Klaus Brockhaus and Walter Oberschelp (oberschelp(AT)informatik.rwth-aachen.de), Dec 28 2004
|
|
|
EXTENSIONS
|
More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008
a(12)-a(14) derived from A102944 by Robert Price, Feb 11 2015
|
|
|
STATUS
|
approved
|
| |
|
|
