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 A125045 Odd primes generated recursively: a(1) = 3, a(n) = Min {p is prime; p divides Q+2}, where Q is the product of previous terms in the sequence. 19
 3, 5, 17, 257, 65537, 641, 7, 318811, 19, 1747, 12791, 73, 90679, 67, 59, 113, 13, 41, 47, 151, 131, 1301297155768795368671, 20921, 1514878040967313829436066877903, 5514151389810781513, 283, 1063, 3027041 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The first five terms comprise the known Fermat primes: A019434. LINKS Sean A. Irvine, Table of n, a(n) for n = 1..64 EXAMPLE a(7) = 7 is the smallest prime divisor of 3 * 5 * 17 * 257 * 65537 * 641 + 2 = 2753074036097 = 7 * 11 * 37 * 966329953. MATHEMATICA a={3}; q=1; For[n=2, n<=20, n++,     q=q*Last[a];     AppendTo[a, Min[FactorInteger[q+2][[All, 1]]]];     ]; a (* Robert Price, Jul 16 2015 *) CROSSREFS Cf. A000945, A019434, A057204-A057208, A051308-A051335, A124984-A124993, A125037-A125045. Sequence in context: A078726 A019434 A164307 * A093179 A067387 A050922 Adjacent sequences:  A125042 A125043 A125044 * A125046 A125047 A125048 KEYWORD nonn AUTHOR Nick Hobson (http://www.qbyte.org/puzzles/), Nov 18 2006 STATUS approved

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Last modified April 3 04:21 EDT 2020. Contains 333195 sequences. (Running on oeis4.)