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A129249 Primes of Erdos-Selfridge class 15-. 3
1432349099, 1749565397, 2771868719, 3790874279, 5288908679, 5804138567, 6273146879, 8123301983, 8594094589, 11055501923, 11809566403, 11914176299, 12647401799, 13432673083, 13925010299, 14208729979 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

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.

LINKS

M. F. Hasler, Table of n, a(n) for n = 1..48

FORMULA

{ 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- }

PROG

(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)

CROSSREFS

Cf. A081640, A081641, A129248, A056637.

Sequence in context: A185931 A069320 A274902 * A165736 A048051 A073519

Adjacent sequences:  A129246 A129247 A129248 * A129250 A129251 A129252

KEYWORD

nonn

AUTHOR

M. F. Hasler, Apr 16 2007, Apr 21 2007

STATUS

approved

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Last modified December 10 20:23 EST 2019. Contains 329909 sequences. (Running on oeis4.)