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A101535 Indices of primes in sequence defined by A(0) = 63, A(n) = 10*A(n-1) + 43 for n > 0. 1
1, 155, 1054, 1996, 8929, 9562, 19559, 26837, 63856 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Numbers n such that (610*10^n - 43)/9 is prime.

Numbers n such that digit 6 followed by n >= 0 occurrences of digit 7 followed by digit 3 is prime.

Some of the larger entries may only correspond to probable primes.

a(10) > 10^5. - Robert Price, Sep 12 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..9.

Makoto Kamada, Prime numbers of the form 677...773.

Index entries for primes involving repunits.

FORMULA

a(n) = A103042(n+1) - 1.

EXAMPLE

673 is prime, hence 1 is a term.

MATHEMATICA

Select[Range[0, 100000], PrimeQ[(610*10^# - 43)/9] &] (* Robert Price, Sep 12 2015 *)

PROG

(PARI) a=63; for(n=0, 2000, if(isprime(a), print1(n, ", ")); a=10*a+43)

(PARI) for(n=0, 2000, if(isprime((610*10^n-43)/9), print1(n, ", ")))

CROSSREFS

Cf. A000533, A002275, A103042.

Sequence in context: A250936 A224336 A218328 * A010086 A110834 A110842

Adjacent sequences:  A101532 A101533 A101534 * A101536 A101537 A101538

KEYWORD

nonn,hard,more

AUTHOR

Klaus Brockhaus and Walter Oberschelp (oberschelp(AT)informatik.rwth-aachen.de), Dec 06 2004

EXTENSIONS

More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 01 2008

a(7)-a(8) from Kamada data by Ray Chandler, Apr 30 2015

a(9) from Robert Price, Sep 12 2015

STATUS

approved

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Last modified April 3 14:34 EDT 2020. Contains 333197 sequences. (Running on oeis4.)