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 A125025 Lengths of rows in A124570. 1
 3, 8, 3, 8, 3 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS This sequence is to A124570 as A123556 is to A124064. a(n) is at most A053669(n)^2, with equality if and only if A053669(n)^2 is the first semiprime in the corresponding arithmetic progression. - Charlie Neder, Jan 10 2019 By subsampling a given arithmetic progression with k terms and distance d one may generate an arithmetic progression of a larger distance d*b, b=1,2,3...., with 1+(k-1)/b terms: a(b*n) >= 1+floor( (a(n)-1)/b ), b=1,2,3..... - R. J. Mathar, Aug 02 2021 18 <= a(6) <= 24. - Jinyuan Wang, Aug 06 2021 a(12) >= 17.  a(18) >= 18.  a(24) >= 18.  a(30) >= 21.  a(36) >= 19.  a(42) >= 20. a(6006) >= 24 (starting 652744562555081).  Hugo van der Sanden, Aug 14 2021 LINKS CROSSREFS Cf. A001358, A123556, A124064, A124570, A091016 (for n=6). Sequence in context: A333287 A117240 A151857 * A309345 A010706 A204998 Adjacent sequences:  A125022 A125023 A125024 * A125026 A125027 A125028 KEYWORD nonn,hard,more AUTHOR Jonathan Vos Post, Nov 15 2006 STATUS approved

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Last modified September 24 21:05 EDT 2021. Contains 347651 sequences. (Running on oeis4.)