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 A195307 Where records occur in A129308 and also in A195155. 2
 1, 2, 6, 12, 60, 180, 360, 420, 840, 1260, 2520, 5040, 13860, 27720, 55440, 83160, 166320, 277200, 360360, 720720, 1081080, 2162160, 2827440, 4324320, 6126120, 12252240, 24504480, 36756720, 73513440, 147026880, 183783600, 232792560, 367567200, 465585120, 698377680 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Observation: a(n) ending at 0, if 5 <= n <= 24 and possibly more. From David A. Corneth, Apr 14 2021: (Start) Conjecture: for each term k > 1 in the sequence there exists prime p such that k/p is in the sequence. From the first 35 terms only a(23) = 2827440 is not in A025487. In the list of conjectured terms, if actual terms <= 10^16 are 97-smooth and have the following property: a(n+1) = a(n) + k*gcd(a(n), a(n-1), ..., a(n-20)) setting a(n) = 1 for n < 1 then those terms are actual terms. The conjectured terms are 41-smooth and satisfy a(n+1) = a(n) + k*gcd(a(n), a(n-1), ..., a(n-13)). (End) LINKS David A. Corneth, Conjectured terms <= 10^16 (a(1)..a(35) are certain) CROSSREFS Cf. A007862, A088726, A093687, A097212, A129308, A181826, A195155. Sequence in context: A139315 A014767 A002319 * A101657 A104371 A104350 Adjacent sequences:  A195304 A195305 A195306 * A195308 A195309 A195310 KEYWORD nonn AUTHOR Omar E. Pol, Oct 16 2011 EXTENSIONS More terms a(6)-a(24) from Alois P. Heinz, Oct 16 2011 a(25)-a(35) from David A. Corneth, Apr 14 2021 STATUS approved

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Last modified June 12 09:24 EDT 2021. Contains 344946 sequences. (Running on oeis4.)