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A101734 Indices of primes in sequence defined by A(0) = 41, A(n) = 10*A(n-1) + 71 for n > 0. 1
0, 462 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Numbers n such that (440*10^n - 71)/9 is prime.

Numbers n such that digit 4 followed by n >= 0 occurrences of digit 8 followed by digit 1 is prime.

Number corresponding to term 462 is a certified prime. No further terms up to 5000.

a(3) > 2*10^5. - Robert Price, Oct 15 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..2.

Makoto Kamada, Prime numbers of the form 488...881.

Index entries for primes involving repunits.

FORMULA

a(n) = A102997(n) - 1.

EXAMPLE

41 is prime, hence 0 is a term.

PROG

(PARI) a=41; for(n=0, 1500, if(isprime(a), print1(n, ", ")); a=10*a+71)

(PARI) for(n=0, 1500, if(isprime((440*10^n-71)/9), print1(n, ", ")))

CROSSREFS

Cf. A000533, A002275, A102997.

Sequence in context: A277989 A138956 A107121 * A059025 A267200 A094380

Adjacent sequences:  A101731 A101732 A101733 * A101735 A101736 A101737

KEYWORD

nonn,bref,hard,more

AUTHOR

Klaus Brockhaus and Walter Oberschelp (oberschelp(AT)informatik.rwth-aachen.de), Dec 14 2004

STATUS

approved

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Last modified July 21 19:25 EDT 2019. Contains 325199 sequences. (Running on oeis4.)