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 A100008 #27 Jan 28 2023 12:14:35
%S A100008 2,2,4,2,4,4,4,2,4,4,4,4,4,4,8,2,4,4,4,4,8,4,4,4,4,4,4,4,4,8,4,2,8,4,
%T A100008 8,4,4,4,8,4,4,8,4,4,8,4,4,4,4,4,8,4,4,4,8,4,8,4,4,8,4,4,8,2,8,8,4,4,
%U A100008 8,8,4,4,4,4,8,4,8,8,4,4,4,4,4,8,8,4,8,4,4,8,8,4,8,4,8,4,4,4,8,4,4,8,4,4,16
%N A100008 Number of unitary divisors of 2n.
%C A100008 b(n) = a(n)/a(1) is multiplicative with b(2^e) = 1, b(p^e) = 2 otherwise. - _David W. Wilson_, Jun 12 2005
%H A100008 Antti Karttunen, <a href="/A100008/b100008.txt">Table of n, a(n) for n = 1..10000</a>
%F A100008 a(n) = A000079(A099812(n)) = A000079(A001221(2n)) = 2*A068068(n). - _Antti Karttunen_, Sep 14 2017
%F A100008 Dirichlet g.f.: 2*zeta(s)^2/(zeta(2*s)*(1+1/2^s)). - _Amiram Eldar_, Jan 28 2023
%F A100008 Sum_{k=1..n} a(k) ~ 8*n*((log(n) - 1 + 2*gamma + log(2)/3)/Pi^2 - 12*zeta'(2)/Pi^4), where gamma is the Euler-Mascheroni constant A001620. - _Vaclav Kotesovec_, Jan 28 2023
%e A100008 a(6)=4 because among the six divisors of 12 only 1,3,4 and 12 are unitary.
%p A100008 with(numtheory): for n from 1 to 120 do printf(`%d,`,2^nops(ifactors(2*n)[2])) od: # _Emeric Deutsch_, Dec 24 2004
%t A100008 a[n_] := 2^PrimeNu[2*n]; Array[a, 100] (* _Amiram Eldar_, Jan 28 2023 *)
%o A100008 (PARI) A100008(n) = 2^omega(2*n); \\ _Antti Karttunen_, Sep 14 2017
%Y A100008 Bisection of A034444, twice A068068.
%Y A100008 Cf. A000079, A001221, A099812.
%K A100008 nonn,easy
%O A100008 1,1
%A A100008 _N. J. A. Sloane_, Nov 20 2004
%E A100008 More terms from _Emeric Deutsch_, Dec 24 2004