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 A336475 #28 Sep 21 2023 01:46:11 %S A336475 1,1,6,1,10,6,14,1,27,10,22,6,26,14,60,1,34,27,38,10,84,22,46,6,75,26, %T A336475 108,14,58,60,62,1,132,34,140,27,74,38,156,10,82,84,86,22,270,46,94,6, %U A336475 147,75,204,26,106,108,220,14,228,58,118,60,122,62,378,1,260,132,134,34,276,140,142,27,146,74,450,38,308,156 %N A336475 Multiplicative with a(2^e) = 1, and for odd primes p, a(p^e) = (e+1)*p^e. %C A336475 Dirichlet convolution of A000265 with itself, divided by A001511(n). %C A336475 Although for all i, j: A003602(i) = A003602(j) => a(i) = a(j), it is not true that a(i) = a(j) => A003602(i) = A003602(j), because A038040 has a duplicate occurrence of a term on at least two odd positions: A038040(1875) = A038040(3125) = 18750. %H A336475 Antti Karttunen, <a href="/A336475/b336475.txt">Table of n, a(n) for n = 1..16384</a> %H A336475 Antti Karttunen, <a href="/A336475/a336475.txt">Data supplement: n, a(n) computed for n = 1..65537</a> %F A336475 a(n) = A038040(A000265(n)). %F A336475 a(n) = A000265(n) * A001227(n). %F A336475 a(n) = (A000005(n) * A000265(n)) / A001511(n). [See the first comment] %F A336475 From _Amiram Eldar_, Sep 21 2023: (Start) %F A336475 Dirichlet g.f.: ((2^s - 2)^2/(4^s - 2^s)) * zeta(s-1)^2. %F A336475 Sum_{k=1..n} a(k) ~ (n^2/12) * (2*log(n) + 4*gamma + 10*log(2)/3 - 1), where gamma is Euler's constant (A001620). (End) %t A336475 f[p_, e_] := (e+1)*p^e; f[2, e_] := 1; a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; Array[a, 100] (* _Amiram Eldar_, Sep 21 2023 *) %o A336475 (PARI) A336475(n) = { my(f=factor(n)); prod(i=1, #f~, if(2==f[i,1],1,(1+f[i,2]) * (f[i,1]^f[i,2]))); }; %o A336475 (Python) %o A336475 from sympy import divisor_count %o A336475 def A336475(n): return (m:=n>>(~n&n-1).bit_length())*divisor_count(m) # _Chai Wah Wu_, Jul 13 2022 %Y A336475 Cf. A000005, A000265, A001227, A001511, A001620, A003602, A038040, A336476. %K A336475 nonn,easy,mult %O A336475 1,3 %A A336475 _Antti Karttunen_, Jul 30 2020