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 A339580 Indices of records in A339579. 2
 1, 3, 90, 1122660, 19099920, 85864770, 26089808580, 554688278430, 4090932431513070, 95405042230542330 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS The records themselves begin 4,5,6,7,8,9,10,12,13,14. a(11) <=  90616211958465842220. REFERENCES Carl Pomerance, Problem 81:21 (= 321), in R. K. Guy problem list. LINKS R. K. Guy, editor, Western Number Theory Problems, 1985-12-21 & 23, Typescript, Jul 13 1986, Dept. of Math. and Stat., Univ. Calgary, 11 pages. Annotated scan of pages 1, 3, 7, 9, with permission. FORMULA a(n) = A339581(n) + 1 for n >= 2. - David A. Corneth, Dec 24 2020 EXAMPLE 90 is in the sequence as A339579(90) = 6 (90*2^k - 1 is prime for k = 0..5 and composite for k = 6) and A339579(m) < 6 for m < 90. - David A. Corneth, Dec 24 2020 CROSSREFS Cf. A063377, A124514, A125113, A339579, A339581. Sequence in context: A053996 A218143 A203477 * A115704 A066751 A115886 Adjacent sequences:  A339577 A339578 A339579 * A339581 A339582 A339583 KEYWORD nonn,more AUTHOR N. J. A. Sloane, Dec 24 2020 EXTENSIONS a(8)-a(10) were taken from A057331 and the bound on a(11) was taken from A005602. - David A. Corneth and Amiram Eldar, Dec 25 2020 STATUS approved

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Last modified August 15 02:13 EDT 2022. Contains 356122 sequences. (Running on oeis4.)