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Search: id:A129249
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| A129249 |
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Primes of Erdos-Selfridge class 15-. |
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+0
3
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| 1432349099, 1749565397, 2771868719, 3790874279, 5288908679, 5804138567, 6273146879, 8123301983, 8594094589, 11055501923, 11809566403, 11914176299, 12647401799, 13432673083, 13925010299, 14208729979
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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The fastest way to calculate the complete list of class N primes up to P is to use the given formula (or PARI function nextclass()) with the list of class (N-1) primes up to P/2.
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LINKS
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M. F. Hasler, Table of n, a(n) for n=1..48
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FORMULA
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{ a(n) } = { p = 2*m*A129248(k)+1 | k=1,2,3... and m=1,2,3... such that p is prime and m has no factor of class > 14- }
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PROGRAM
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(PARI) class(n, s=1) = { if(!isprime(n), 0, if(!(n=factor(n+s)[, 1]) | n[ #n]<=3, 1, for(i=2, #n, n[1]=max(class(n[i], s)+1, n[1])); n[1]))} nextclass(a, s=-1, p, n=[])={if(!p, p=nextprime(a[ #a]+1)); print("producing primes of class ", 1+class(a[1], s), ["+", "-"][1+(s<0)], " up to 2*", p); for(i=1, #a, for(k=1, p/a[i], if(isprime(2*k*a[i]-s), n=concat(n, 2*k*a[i]-s)))); vecsort(n)} A129249=nextclass(A129248)
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CROSSREFS
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Cf. A081640, A081641, A129248, A056637.
Sequence in context: A114888 A105015 A069320 this_sequence A048051 A073519 A034616
Adjacent sequences: A129246 A129247 A129248 this_sequence A129250 A129251 A129252
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KEYWORD
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nonn
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AUTHOR
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M. F. Hasler (Maximilian.Hasler(AT)gmail.com), Apr 16 2007, Apr 21 2007
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