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A101568 Indices of primes in sequence defined by A(0) = 53, A(n) = 10*A(n-1) - 27 for n > 0. 1
0, 1, 2, 7, 17, 19, 30, 41, 102, 174, 180, 530, 705, 1076, 1176, 1551, 19736, 32196, 51507, 58274, 62232, 90032 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Numbers n such that 50*10^n + 3 is prime.

Numbers n such that digit 5 followed by n >= 0 occurrences of digit 0 followed by digit 3 is prime.

Numbers corresponding to terms <= 705 are certified primes.

a(23) > 2*10^5. - Robert Price, Aug 03 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..22.

Makoto Kamada, Prime numbers of the form 500...003.

FORMULA

a(n) = A096254(n) - 1.

EXAMPLE

5003 is prime, hence 2 is a term.

MATHEMATICA

Select[Range[0, 200000], PrimeQ[50*10^# + 3] &] (* Robert Price, Aug 03 2015 *)

PROG

(PARI) a=53; for(n=0, 1500, if(isprime(a), print1(n, ", ")); a=10*a-27)

(PARI) for(n=0, 1500, if(isprime(50*10^n+3), print1(n, ", ")))

CROSSREFS

Cf. A000533, A002275, A096254.

Sequence in context: A023300 A317308 A045378 * A291528 A182575 A074884

Adjacent sequences:  A101565 A101566 A101567 * A101569 A101570 A101571

KEYWORD

nonn,more

AUTHOR

Klaus Brockhaus and Walter Oberschelp (oberschelp(AT)informatik.rwth-aachen.de), Dec 09 2004

EXTENSIONS

1551 from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 01 2008

a(17)-a(22) from Kamada data by Ray Chandler, Apr 30 2015

STATUS

approved

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Last modified November 12 14:43 EST 2019. Contains 329058 sequences. (Running on oeis4.)