cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A330486 Earliest start of a run of n numbers divisible by a seventh power larger than one.

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%I A330486 #23 Dec 19 2019 12:33:36
%S A330486 128,76544,2372890624,390491792890623,2083234733888734218749,
%T A330486 18962123650219836035505781245
%N A330486 Earliest start of a run of n numbers divisible by a seventh power larger than one.
%C A330486 In De Koninck's book, a(4) was probable but not certain.  It also gives probable terms for a(5) and a(6).
%C A330486 From _David A. Corneth_, Dec 18 2019: (Start)
%C A330486 a(6) <= 18962123650219836035505781245
%C A330486 a(7) <= 105574810222799317012520534891328125
%C A330486 a(8) <= 352061173826332779662070232460962002804453118
%C A330486 a(9) <= 74322635218313783849790472504951802188239215127109371
%C A330486 If any a(k) of these values are less than presented values, one of a(k) + m is divisible only by at least one p^7 for some p > 31, 0 <= m < k.
%C A330486 For a(6) this minimum prime is some prime p > 59. (End)
%D A330486 J.-M. De Koninck, Those Fascinating Numbers, Entry 242, p. 63, Amer. Math. Soc., 2009.
%H A330486 David A. Corneth, <a href="/A330486/a330486.gp.txt">PARI program for finding candidates</a>
%H A330486 Jean-Marie De Koninck, <a href="https://bookstore.ams.org/mbk-64/83">Those Fascinating Numbers</a>, Amer. Math. Soc., (2009), page 63.
%e A330486 2372890624 is divisible by 2^7, 2372890625 is divisible by 5^7, 2372890626 is divisible by 3^7.  This is the smallest number with this property, so a(3)=2372890624.
%Y A330486 Cf. A045882, A271443, A001015.
%K A330486 nonn,more,hard
%O A330486 1,1
%A A330486 _Jud McCranie_, Dec 15 2019
%E A330486 a(5) from _Giovanni Resta_, Dec 17 2019
%E A330486 a(6) from _Giovanni Resta_, Dec 19 2019