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 A165499 First term of maximal arithmetic progression with difference n, such that each term k has tau(k) = n. 4
 1, 3, 4, 5989, 16 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS a(6) <= 161804009483982959337354063701 if A165498(6) = 9, and at least 1e14. a(8) = 380017309607. a(10) <= 43920665884407841463671 if A165498(10) = 5 (found by Giovanni Resta), and at least 1e12. a(12) <= 11673662470957217427690002629075 if A165498(12) = 10, and at least 1e10. a(16) = 2a(8). A165498(n) = 1 for odd n, so a(7) = 64; a(9) = 36; a(11) = 1024; a(13) = 4096; a(15) = 144; etc. LINKS EXAMPLE A165498(4) = 8, and exhaustive search finds tau(5989) = tau(5993) = tau(5997) = tau(6001) = tau(6005) = tau(6009) = tau(6013) = tau(6017) = 4 is the first example of an 8-term progression, so a(4) = 5989. CROSSREFS Cf. A064491, A165497, A165498, A165501. Sequence in context: A305169 A316759 A153063 * A094396 A161838 A152624 Adjacent sequences:  A165496 A165497 A165498 * A165500 A165501 A165502 KEYWORD hard,nonn,more AUTHOR Hugo van der Sanden, Sep 21 2009; updated Nov 29 2016 STATUS approved

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Last modified September 18 02:20 EDT 2019. Contains 327149 sequences. (Running on oeis4.)