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Search: id:A101833
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| A101833 |
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Indices of primes in sequence defined by A(0) = 37, A(n) = 10*A(n-1) - 23 for n > 0. |
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1
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OFFSET
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1,3
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COMMENT
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Numbers n such that (310*10^n + 23)/9 is prime.
Numbers n such that digit 3 followed by n >= 0 occurrences of digit 4 followed by digit 7 is prime.
Numbers corresponding to terms <= 757 are certified primes.
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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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Makoto Kamada, Factorizations of near-repdigit numbers.
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EXAMPLE
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347 is prime, hence 1 is a term.
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MATHEMATICA
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For[n=0, n <= 4000, n++, If[PrimeQ[(310*10^n + 23)/9], Print[n]]] (Steinerberger)
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PROGRAM
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(PARI) a=37; for(n=0, 1500, if(isprime(a), print1(n, ", ")); a=10*a-23)
(PARI) for(n=0, 1500, if(isprime((310*10^n+23)/9), print1(n, ", ")))
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CROSSREFS
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Cf. A000533, A002275.
a(n) = A102969(n) - 1.
Sequence in context: A004048 A037191 A035853 this_sequence A068683 A104336 A105547
Adjacent sequences: A101830 A101831 A101832 this_sequence A101834 A101835 A101836
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KEYWORD
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nonn,hard
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AUTHOR
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Klaus Brockhaus (klaus-brockhaus(AT)t-online.de) and Walter Oberschelp (oberschelp(AT)informatik.rwth-aachen.de), Dec 20 2004
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EXTENSIONS
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a(5) from Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Feb 04 2006
More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008
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