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 A261411 a(1)=1; thereafter a(n) = smallest prime factor of A261570(n). 2
 1, 11, 3, 11, 41, 3, 239, 11, 3, 11, 11, 3, 11, 11, 3, 11, 11, 3, 71, 21557, 19, 17, 31, 181, 17, 353, 19, 31, 19, 29, 17, 29, 11616377, 214141, 19, 5471, 17, 13883, 3, 7, 421219193, 3, 17, 7, 3, 7, 101, 3, 634324033999, 13, 19, 13, 83, 13, 23, 13, 19, 13, 19 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS David Broadhurst and Hiroaki Yamanouchi, Table of n, a(n) for n = 1..99 (First 61 terms from Hiroaki Yamanouchi) EXAMPLE A261570(11) = 12345678911987654321 = (11)(59)(34631)(43117)(6373)(1999), so a(10) = 11. Note that a(2007) = A261570(2007) is a 21233-digit (probable) prime. CROSSREFS Cf. A261570, A067063, A075023. Sequence in context: A194706 A110435 A110774 * A067063 A075023 A205960 Adjacent sequences:  A261408 A261409 A261410 * A261412 A261413 A261414 KEYWORD nonn AUTHOR N. J. A. Sloane, Aug 24 2015, based on Robert G. Wilson v's comment in A261570. EXTENSIONS a(41)-a(59) from Hiroaki Yamanouchi, Aug 24 2015 STATUS approved

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Last modified December 12 09:36 EST 2019. Contains 329953 sequences. (Running on oeis4.)