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 A101871 #10 Sep 23 2023 03:41:17
%S A101871 1,1,1,1,2,1,1,1,1,1,1,1,2,3,1,1,1,1,1,1,1,1,2,1,2,1,1,1,1,1,1,2,1,1,
%T A101871 1,1,1,2,1,1,5,1,1,1,1,1,1,1,1,2,1,1,1,1,1,1,1,1,2,1,2,1,3,1,1,1,1,3,
%U A101871 1,1,1,1,1,2,1,1,2,1,1,1,1,1,1,1,2,2,1,2,1,1,1,1,1,1,3,1,1,1,1,1,1,1,1,2,1
%N A101871 Number of Abelian groups of order 2n+1.
%F A101871 From _Amiram Eldar_, Sep 23 2023: (Start)
%F A101871 a(n) = A000688(2*n+1) = A000688(4*n+2).
%F A101871 Asymptotic mean: Limit_{m->oo} (1/m) * Sum_{k=1..m} a(k) = 2 * A048651 * A021002 = 1.32545452721253858057... . (End)
%t A101871 a[n_] := FiniteAbelianGroupCount[2*n + 1]; Array[a, 100, 0] (* _Amiram Eldar_, Sep 23 2023 *)
%Y A101871 Bisection of A000688.
%Y A101871 Cf. A021002, A048651.
%K A101871 nonn,easy
%O A101871 0,5
%A A101871 _N. J. A. Sloane_, Jan 28 2005
%E A101871 More terms from _Joshua Zucker_, May 10 2006