|
Search: id:A101841
|
|
|
| A101841 |
|
Indices of primes in sequence defined by A(0) = 31, A(n) = 10*A(n-1) + 61 for n > 0. |
|
+0
1
|
| |
|
|
OFFSET
|
1,2
|
|
|
COMMENT
|
Numbers n such that (340*10^n - 61)/9 is prime.
Numbers n such that digit 3 followed by n >= 0 occurrences of digit 7 followed by digit 1 is prime.
Numbers corresponding to terms <= 357 are certified primes.
|
|
REFERENCES
|
Klaus Brockhaus and Walter Oberschelp, Zahlenfolgen mit homogenem Ziffernkern, MNU 59/8 (2006), pp. 462-467.
|
|
EXAMPLE
|
377771 is prime, hence 4 is a term.
|
|
PROGRAM
|
(PARI) a=31; for(n=0, 1500, if(isprime(a), print1(n, ", ")); a=10*a+61)
(PARI) for(n=0, 1500, if(isprime((340*10^n-61)/9), print1(n, ", ")))
|
|
CROSSREFS
|
Cf. A000533, A002275.
a(n) = A102976(n) - 1.
Sequence in context: A134794 A093852 A065573 this_sequence A061609 A136465 A047939
Adjacent sequences: A101838 A101839 A101840 this_sequence A101842 A101843 A101844
|
|
KEYWORD
|
nonn,hard,more
|
|
AUTHOR
|
Klaus Brockhaus (klaus-brockhaus(AT)t-online.de) and Walter Oberschelp (oberschelp(AT)informatik.rwth-aachen.de), Dec 20 2004
|
|
|
Search completed in 0.002 seconds
|
