A372784 - OEIS

%I #8 May 13 2024 12:22:05

%S 3,4,6,5,6,8,6,6,9,8,6,10,6,8,12,7,6,12,6,10,12,8,6,12,9,8,12,10,6,16,

%T 6,8,12,8,12,15,6,8,12,12,6,16,6,10,18,8,6,14,9,12,12,10,6,16,12,12,

%U 12,8,6,20,6,8,18,9,12,16,6,10,12,16,6,18,6,8,18,10

%N a(n) = tau(4*n) = A000005(4*n).

%H Vaclav Kotesovec, <a href="/A372784/a372784.jpg">Graph - the asymptotic ratio (100000 terms)</a>

%F For n > 1, a(n) = A366872(n-2).

%F Sum_{k=1..n} a(k) ~ (8*n*(log(n) + 2*gamma - 1) + n*4*log(2)) / 4, where gamma is the Euler-Mascheroni constant A001620.

%t Table[DivisorSigma[0, 4*n], {n, 1, 150}]

%Y Cf. A193553, A366872.

%Y Cf. A000005, A099777, A372713, A372785, A372786, A372787, A372788, A372789, A372790, A372791, A372792.

%K nonn

%O 1,1

%A _Vaclav Kotesovec_, May 13 2024