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 A068815 Primes with a 4 followed by 1's. 2
 41, 4111, 41111111111111, 41111111111111111111111111, 4111111111111111111111111111111111111111111111111111111111111111111111111 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The next term a(6) has 109 digits and is too large to be displayed here. LINKS Harvey P. Dale, Table of n, a(n) for n = 1..10 Makoto Kamada, Prime numbers of the form 411...11. MATHEMATICA Select[Table[FromDigits[PadRight[{4}, n, 1]], {n, 1000}], PrimeQ] (* Harvey P. Dale, Sep 15 2019 *) PROG (PARI) for(n=1, 200, if(isprime(4*10^n+(10^(n)-1)/9)==1, print1(4*10^n+(10^(n)-1)/9, ", "))) CROSSREFS Cf. A002275, A056706 (corresponding values of n). Sequence in context: A233015 A282054 A107690 * A093174 A280677 A209104 Adjacent sequences:  A068812 A068813 A068814 * A068816 A068817 A068818 KEYWORD nonn,base AUTHOR Amarnath Murthy, Mar 07 2002 EXTENSIONS More terms from Benoit Cloitre, Mar 09 2002 STATUS approved

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Last modified May 26 13:49 EDT 2020. Contains 334626 sequences. (Running on oeis4.)