|
|
A101140
|
|
Indices of primes in sequence defined by A(0) = 73, A(n) = 10*A(n-1) + 13 for n > 0.
|
|
1
|
|
|
|
OFFSET
|
1,3
|
|
COMMENTS
|
Numbers n such that (670*10^n - 13)/9 is prime.
Numbers n such that digit 7 followed by n >= 0 occurrences of digit 4 followed by digit 3 is prime.
Numbers corresponding to terms <= 105 are certified primes.
|
|
REFERENCES
|
Klaus Brockhaus and Walter Oberschelp, Zahlenfolgen mit homogenem Ziffernkern, MNU 59/8 (2006), pp. 462-467.
|
|
LINKS
|
|
|
FORMULA
|
|
|
EXAMPLE
|
73 is prime, hence 0 is a term.
|
|
MATHEMATICA
|
For[n=0, n < 4000, n++, If[PrimeQ[(670*10^n - 13)/9], Print[n]]] (Steinerberger)
|
|
PROG
|
(PARI) a=73; for(n=0, 1000, if(isprime(a), print1(n, ", ")); a=10*a+13)
(PARI) for(n=0, 1000, if(isprime((670*10^n-13)/9), print1(n, ", ")))
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,hard
|
|
AUTHOR
|
Klaus Brockhaus and Walter Oberschelp (oberschelp(AT)informatik.rwth-aachen.de), Dec 03 2004
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|