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.
%I A173669 #14 Mar 27 2024 21:06:06
%S A173669 1,2,3,12,26,31,84,119,248,1107,1543,1683
%N A173669 Numbers k which divide number of groups of order <= k (A063756).
%C A173669 No other terms up to 2047. - _Eric M. Schmidt_, Feb 10 2013
%F A173669 {k: k | A063756(k)} == {k: k | SUM[i=1..k] A000001(i)}.
%e A173669 a(1) = 1 because 1 divides (the number of groups of order <= 1) = (number of groups of order 1) = 1.
%e A173669 a(4) = 12 because 12 divides (the number of groups of order <= 12) = 24.
%e A173669 a(5) = 26 because 26 divides (the number of groups of order <= 26) = 78 = 3 * 26.
%e A173669 a(6) = 31 because 31 divides (the number of groups of order <= 31) = 93 = 3 * 31.
%o A173669 (GAP) A173669 := function(max) local n, res, i; n := 0; res := []; for i in [1..max] do n := n + NrSmallGroups(i); if n mod i = 0 then Add(res, i); fi; od; return res; end; # _Eric M. Schmidt_, Feb 10 2013
%Y A173669 Cf. A000001, A063756.
%K A173669 nonn,more
%O A173669 1,2
%A A173669 _Jonathan Vos Post_, Nov 24 2010
%E A173669 More terms from _Eric M. Schmidt_, Feb 10 2013