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Search: id:A105526
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| A105526 |
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Smallest prime that becomes a product of n distinct primes when a 1 is prepended to it. |
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+0
2
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| 3, 5, 113, 1193, 13883, 312311, 10861751, 209551343, 10705778183, 307525001783, 10418232047123, 795076554810539, 17714426958677549, 1015246475642397989, 100019969411961789191, 1728838135940697098327, 165000496158437438012513
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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We have a(2)=5 because 5 is the smallest prime (ahead of 11,19,19,23,29,...) that is a product of two distinct primes when a 1 is prepended.
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PROGRAM
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(PARI) {len10(n) = ceil(log(n+1)/log(10))} {r(n, p, d)=local(q); if(d==0, k=n-10^(len10(n)-1); if(len10(k)==len10(n)-1 && isprime(k), m=n); return); q=nextprime(p+1); while(n*q^d<m, r(n*q, q, d-1); q=nextprime(q+1))} {A105526(d) = M=3^d; while(1, m=M; r(1, 2, d); if(m!=M, return(m%10^(len10(m)-1))); M*=2)} (Alekseyev)
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CROSSREFS
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Cf. A105525.
Sequence in context: A054266 A054268 A153137 this_sequence A070743 A103993 A088269
Adjacent sequences: A105523 A105524 A105525 this_sequence A105527 A105528 A105529
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KEYWORD
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nonn,base
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AUTHOR
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Lekraj Beedassy (blekraj(AT)yahoo.com), Apr 11 2005
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EXTENSIONS
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a(5)-a(8) from Ray Chandler (rayjchandler(AT)sbcglobal.net), Apr 21 2005
More terms from Max Alekseyev (maxale(AT)gmail.com), Apr 28 2005
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