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A102006
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Indices of primes in sequence defined by A(0) = 13, A(n) = 10*A(n-1) - 27 for n > 0.
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5
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0, 1, 4, 5, 10, 16, 17, 38, 55, 100, 104, 106, 122, 412, 425, 2606, 7667, 10469, 11020, 17752, 26926, 60775, 98287, 300475
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OFFSET
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1,3
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COMMENTS
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Numbers n such that 10*10^n + 3 is prime.
Numbers n such that digit 1 followed by n >= 0 occurrences of digit 0 followed by digit 3 is prime.
Numbers corresponding to terms <= 425 are certified primes.
No other terms <99,999.
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REFERENCES
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Klaus Brockhaus and Walter Oberschelp, Zahlenfolgen mit homogenem Ziffernkern, MNU 59/8 (2006), pp. 462-467.
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LINKS
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Table of n, a(n) for n=1..24.
Makoto Kamada, Prime numbers of the form 100...003.
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FORMULA
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a(n) = A049054(n) - 1.
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EXAMPLE
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100003 is prime, hence 4 is a term.
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PROG
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(PARI) a=13; for(n=0, 1500, if(isprime(a), print1(n, ", ")); a=10*a-27)
(PARI) for(n=0, 1500, if(isprime(10*10^n+3), print1(n, ", ")))
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CROSSREFS
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Cf. A000533, A002275, A049054, A159352.
Sequence in context: A135104 A131780 A354968 * A118735 A002970 A073611
Adjacent sequences: A102003 A102004 A102005 * A102007 A102008 A102009
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KEYWORD
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nonn,hard,more
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AUTHOR
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Klaus Brockhaus and Walter Oberschelp (oberschelp(AT)informatik.rwth-aachen.de), Dec 28 2004
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EXTENSIONS
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More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008
a(22)=60775, a(23)=98287 from Robert Price, Mar 03 2011
a(24) from A049054 by Ray Chandler, May 01 2015
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STATUS
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approved
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